In 25 B.C., Galatia (in central Turkey), which was a client state of Rome, was converted to a Roman province without any fighting after the king of Galatia was murdered. Augustus fought in the Cantabrian Wars (29-19 B.C.) and took Cantabria,Asturias and León In the northwest of Spain. This completed the conquest of Hispania (Spain and Portugal).

In 16 B.C., Noricum (eastern and central Austria and part of Slovenia.) was annexed to the empire. Noricum had been a client state of the Romans, traded with the Romans and had supported Julius Caesar in his civil war. However, when it joined and invasion of Histria (a peninsula next to Italy) by the Pannonians it was annexed. No fighting occurred. Noricum remained a kingdom, but it was put under the supervision of a Roman procurator (financial manager). In 15 B.C., Augustus' generals, Tiberius and Drusus, subjugated Raetia (eastern and central Switzerland, part of southern Germany and part of eastern Austria). This Alpine Area was seen as a buffer against possible invasions of Italy.

In 6-9 A.D., the Pannonians, with the Dalmatians and other Illyrian tribes, engaged in the Great Illyrian Revolt, which was suppressed by Augustus' generals, Tiberius and Germanicus, after three years of war. Pannonia (eastern Austria, northern Slovenia, northern Croatia, western Hungary, western Slovakia, north-western Serbia, and northern Bosnia and Herzegovina) was annexed.

In 13 B.C. in response to attacks by Germanic peoples, Drusus penetrated deeply into German territory and into Holland and Frisia. In 10 B.C. and 9 B.C. he defended his conquests and made further gains. Hoverer, three legions were slain by a Germanic coalition at the Battle of e Battle of the Teutoburg Forest in 9 A.D. Augustus decided to retreat and re-establish the River Rhine as the frontier of the empire. After Augustus' death several attack were carried out beyond the Rhine and the Germanic people suffered heavy losses. However, the Romans maintained the Rhine as their frontier. The attacks were carried out as revenge of the defeat at Teutoburg and to defeat Arminus, the leader who defeated the Romans in that battle, because he was seen as a threat to stability in the region.

Under the reign of Octavian/Augustus (historians use Augustus, an honorary title he was given, for the period when he was emperor) a major process of expansion.

Augustus completed the conquest of Spain. He expanded the border of Libya and Tunisia inland. He annexed the easternpart of the coast of Algeria the coast of Morocco on the Atlantic down to Agadir. He annexed two client states: Galatia and Judaea. He annexed Moesia (an area along the Danube which included southern Serbia, northern Macedonia and Bulgaria and the part of Romania across the Danube) after the Scythians attacked a Roman ally. In 16 BC Noricum was annexed following an attack into northeaster Italy by the Pannonians which the people of Noricum joined. They were defeated by the governor of Illyrimucum. In 6 AD Augustus annexed Pannonia (eastern Austria, western Hungary, part of Slovenia and northern Croatia and Serbia) after its people joined the next door Desitiates in the Great Illyrian Revolt which was suppressed by the generals Tiberius and Germanicus. In 13 BC his general Drusus pushed deep into Germany following attacks into northern Gaul. However, in 9 AD thee Roman legions were routed and Augustus decided to abandon the recent conquests and withdraw the frontier of the empire back to the river Rhine.

During the life of Christ the Roman Empire covered the following modern countries of parts of countries:

Western Europe: Italy, Malta, Spain, Portugal, France, Belgium, Luxembourg, Holland south of the river Rhine, Germany west of the river Rhine and part of southern Germany , Switzerland, and Liechtenstein.

Eastern Europe: part of eastern Austria and western Hungary, Slovenia, Serbia, Croatia, Bosnia and Herzegovina, Montenegro, Macedonia, Albania, Greece.

Asia: Western and central Turkey, Cyprus, Syria, Lebanon, Israel/Palestine.

Africa: Egypt, the coastal part of Libya, Tunisia, the coastal part of eastern Algeria, and a strip of land in northern Morocco.

There were also some client states which were under the Roman sphere of influence: Noricum, which covered most of Austria and part of southern Germany, Thrace, which was in present day Bulgaria, Cappadocia, in central-eastern Turkey, and Mauritania, which covered most of Algeria and the eastern coast of Morocco.

After the life of Christ, the Roman Empire expanded further.

By 60 CE the Roman Empire had almost reached it greatest extent. Only northern England and Dacia (roughly present day Romania) had not been conquered. Between 41 and 54 the emperor Claudius conquered southern England and annexed some Roman client states into the Roman Empire. Two of these were in present day Turkey (Pamphylia and Lycia); one was roughly in present day south-eastern Bulgaria (Thace) and one was in part of Austria, and southern Germany and in Slovenia (Noricum). Claudius also annexed the client state of Mauretania, which was in present day northern Morocco.

The Roman Empire covered the following modern day countries or parts of modern countries:

Western Europe: Italy, Malta, Spain, Portugal, France, Belgium, Luxembourg, Holland south of the river Rhine, southern Germany and part of central Germany, Switzerland, Liechtenstein, Austria and southern England .

Eastern Europe: western Hungary, part of western Slovakia, Slovenia, Serbia, Croatia, Bosnia and Herzegovina, Montenegro, Macedonia, Albania, Greece, and Bulgaria,

Asia: Turkey, Cyprus, Armenia, northern Iraq, Syria, Lebanon, Israel and Palestine, Jordan, and the northern part of the coast of the Red Sea in Saudi Arabia.

Africa: Egypt, the coastal part of Libya, Tunisia, the coastal part of Algeria, and northern Morocco.

Augustus annexed Egypt in 30 BC during the civil wars and extended the borders of the empire in North Africa. He also annexed Galatia (in central Turkey) in 25 BC, Cantabria and Asturias (in northwestern Spain) in 19 BC, Noricum(most of Austria and part of Bavaria in southern Germany and part of Slovenia) in 16 BC, Rhaetia (central and eastern Switzerland, eastern Austria and part of southern Germany) in 15 BC and Pannonia (Eastern Austria and western Hungary) in 9 BC.

Augustus turned the Roman protectorate of Illyricum (northern Albania, Montenegro, Bosnia and Herzegovina and coastal and northwestern Croatia) into a province of the empire sometime between 35 and 33 AD.

Augustus also fought and expanded deep into western Germany, but was defeated at the Battle of the Teutoburg Forest in 9 AD and withdrew back to the previous frontier of the empire along the river Rhine.

Augustus restored order in the empire because, by winning the Final Civil War of the Roman Republic, he became the most powerful man in Rome. He controlled the legions, the spoils of war had made an immensely rich man and he had an extensive network of patronage throughout the empire. He used this to become an absolute ruler. He maintained order and stability though his firm grip on power. However, he had to tread carefully.

Augustus turned himself into an absolute ruler while pretending that he was restoring the republic and that he respected its constitution. He learned from Julius Caesar's mistakes. Caesar wanted to restore the central government's control over the provinces, which had become the personal fiefs of their governors, and the efficiency of the state by concentrating power in his hands. However, he had given the impression that he wanted to become a king, which outraged conservative republicans and was seen as a threat to the republic. As a result, a group of conservative senators assassinated him. Augustus had the same agenda as Caesar, but had learnt that he needed to try not to antagonise the conservatives and the senators.

In the First Settlement he reached with the senate (27 BC) the senate gave him control of the border provinces of the empire (imperial provinces) with a ten year "pacification" mandate, while the senate retained governance of the core provinces (proconsular or senatorial provinces). This gave the idea that the senate and the traditions of the republic had been respected by allowing the senators in remain in charge of the core provinces. However, this institutionalised Augustus's military power. The border provinces had most of the legions, giving Augustus control of 20 legions, while the senate controlled only five. Moreover, it sanctioned Augustus's extra-constitutional power. Constitutionally, only senators could govern the provinces, but the senate agreed to give Augustus the border provinces because he controlled the army. He was also made permanent consul (head of state), even though the term of office of consuls was meant to be one year and consuls were meant to be elected. As such, he also had power over the governors appointed by the senate.

Augustus also used other tactics to maintain his pretence that he was restoring and preserving the republic. He retained the popular assembly and its right to vote on bills and to elect the officers of state. However, he became the real legislator and only made token submissions of bills for the assembly to vote on. He retained the officers of state of the republic and their election by the assembly. However, this was just a formality because he created his own administration and the state was run by officials appointed by him. He revived archaic religious cults which had been forgotten to portray himself as a champion of tradition. However, he had Caesar deified, called himself son of the divine Caesar and created a religious cult centred on his person like Caesar had done. He chose the title of Princeps, which roughly means first man. He derived this title from that of the Princeps Senatus, who was the first among equals of the senate, was the eldest senator, the first member of of the senate by precedence and could speak first. Augustus pretended that he was a first among equals and that he ruled in conjunction with the senate while acting as an absolute and turning the senate into an instrument for his power. He took up some precedents set by Caesar. He had the senate bestowing titles on him: Princeps and Augustus (the illustrious one) which was a religious rather that a political title.

With regard to foreign policy, Augustus' rule was one of the most expansionist ones in Roman history. He completed the conquest of Spain. He expanded the border of Libya and Tunisia inland. He took over the eastern part of the coast of Algerian and part of the northern coast of Morocco on the Atlantic. He annexed two client states: Galatia and Judaea. There were other conquests as well.

In 15 BC Augustus sent the brothers Tiberius and Drusus conquer Rhaetia. This region covered eastern and central Switzerland, part of southern Germany, most of the Tirol (in eastern Austria and the next door area of Italy) and part of Lombardy (in Italy). In 16 BC Publius Silius, proconsul (governor) of Illyricum annexed Noricum, Which covered most of Austria and past of Slovenia. Noricum had joined the Pannonians in an attack on an area in northeastern Italy.

The conquest of the above alpine regions served as a springboard for the conquest of Germania. In 12 BC Augustus sent Tiberius and Drusus to campaign in Germania. By 9 BC Drusus reached the river Elbe, conquering the rest of southern Germania and central and much of northern Germania. Tiberius launched an operation against the Marcomanni of Bohemia (the Czech Republic). However, he did not conquer them because he had to return to Germania to help there.

Some expansion (like the one into Noricum) was related to attacks or rebellions. A Scythian people from north of the Danube tribe crossed the river and threatened a Roman ally. They were defeated in 29 BC by Marcus Licinius Crassus. Following this Moesia (an area along the Danube which included southern Serbia, northern Macedonia and Bulgaria and the part of Romania across the Danube) was annexed as a Roman province. In AD 6, Daesitiates troops (the Desitiates were a people from central Bosnia and Herzegovina) mutinied and defeated Roman forces set against them. The Pannonians joined the revolt. Augustus ordered Tiberius and Germanicus to deal with the rebellion. He managed to suppress it in 9 BC. Pannonia (eastern Austria, western Hungary, part of Slovenia and northern Croatia and Serbia) was annexed as a roman Province.

In the east, the Parthian Empire (the third of the four pre-Islamic Persian empires) had defeated the Romans in Armenia and captured the standards of legions three times (53, 40 and 36 BC). In 20 BC Augustus sent an army under Agrippa and Tiberius with the aim of turning Armenia into a client state. However, Augustus wished to avoid a long and costly war against the mighty Persians and used this force as leverage for negotiations. A compromise was reached Armenia was turned into a neutral zone and there was no war between these two powers.

Augustus reorganised the Roman legions and regularised them. During the civil wars the leaders of the warring factions had levied and paid their own legions. Augustus reduced the number of legions from 60 to 28 and discharged many soldiers to bring down the size of the army to manageable levels. He settled the discharged soldiers in colonies (settlements) where that were given a plot of land to farm. The size of the Roman was 150,000 men.

Augustus completed the creation of a standing army. This process had begun with the Marian Reforms of the army of 107 BC where soldiers were given a career of 16 years and on discharge, the grant of a sizeable sum of money (nummaria missio) or a plot of land to farm (agraria missio). However, recruitment was carried out by individual military commanders and occurred as and when needed. With Augustus, recruitment was carried out centrally by the emperor's government and soldiers staid in the army all year, not just during the military campaigning season (March to October). Thus the Roman army became a fully standing army. Augustus also increased the length of military service to 20 years and set a 5 year period for reservists, the evocati (singular evocatus) soldiers who enlisted voluntarily after discharge at the invitation of their military commanders.

Augustus reintroduced the auxiliaries, non-Roman soldiers who fought in units which supported the Roman legions which were made up of Roman citizens. Previously these soldiers hag came from Italian peoples who were Roman allies. Since the Italians had been given Roman citizenships, Augustus' auxiliaries were non-Romans form the other parts of the empire. He set the length of their career at 25 years. Their pay was lower. On discharge they were granted the nummaria mission or the agraria mission. In addition, they were also entitled to apply for Roman citizenship. Augustus set the same structure and training as the Roman legions for the auxiliary troops. The number of auxiliaries was the same as that of the legionaries.

Augustus created a separate military treasury (the ell'aerarium militaris) which was financed by taxes on sales and the inheritance tax. Therefore, the soldiers were paid by the imperial government instead of, as previously, by military commanders. This ensured loyalty to the emperor.

Augustus stationed the bulk of the legions in the frontier provinces of the empire because they needed to be defended. He reached a settlement with the senate where the senate retained control of the older provinces of the empire (as it had before) and their legions but he was given control of the border ones and their legions. Since the bulk of the legions were in the frontier provinces, this effectively gave Augustus control over the army

Augustus' rule was one of the most expansionist ones in Roman history. He completed the conquest of Spain, by defeating the Cantabrians of north-western Spain. He expanded the borders of Libya and Tunisia inland. He annexed Mauretania Tingitana(the eastern part of the coast of Algerian and part of the northern coast of Morocco). He annexed two client states: Galatia (in central Turkey) and Judaea. He annexed Moesia (an area along the Danube which included southern Serbia, northern Macedonia, Bulgaria and the part of Romania south of the Danube) after the Scythians attacked a Roman ally there. In 16 BC Noricum (Bavaria, Slovenia and most of Austria) was annexed following an attack into north-eastern Italy by the Pannonians which Noricum joined. In 15 BC he had Rhaetia (central and eastern Switzerland) conquered by his generals. He wanted to secure it to strengthen the defence of Italy form possible attacks form the north. In 6 AD Augustus annexed Pannonia (eastern Austria, western Hungary, and northern Croatia and Serbia) after its people joined the next door Desitiates in the Great Illyrian Revolt which was suppressed by Augustus' generals. In 13 BC his general Drusus pushed deep into centralGermanyfollowing attacks into northern Gaul from there. However, in 9 AD thee Roman legions were routed and Augustus decided to abandon this area and withdraw the frontier of the empire back to the river Rhine.

During the Late Republic the provinces of the Roman Empire were:

Sicilia

(Sicily), Corsica et Sardinia, Gallia Cisalpina(northern Italy), Gallia Narbonensis (southern France), Hispania Ulterior (Iberian peninsula), Hispania Citerior and Illyricum (the eastern coast of the Adriatic Sea), Macedonia (Greece), Asia (in western Turkey), Bithynia et Pontus (northern Turkey), Cilicia et Cyprus (Cyprus and the eastern part of the southern coast of Turkey), Bithynia et Pontus (in northern Turkey), Corduene (in northern Iraq), Creta et Cyrenaica(Crete and eastern Libya), Syria and Africa (western Libya, Tunisia, coastal Algeria and northern Morocco)

During the Principate, the period from the rule of Augustus to the Rule of Numerian (27 BC to 284 AD) the provinces of the Roman Empire were:

Sicilia

(Sicily), Corsica et Sardinia, Gallia Cisalpina(northern Italy), Britannia Superior (northern England and southern Scotland), Britannia Inferior (Wales and central and southern England), Hispania Citerior (eastern Spain), Hispania Ulterior (northern and central Spain), Hispania Baetica (southern Spain), Lusitania (Portugal and part of eastern Spain), Gallia Aquitania (southeastern France), Alpes Maritimae, Alpes Poeninae and Alpes Cottiae, (the Alpine areas of southeastern France), Gallia Belgica (Belgium), Gallia Lugdunensis (central and northern France), Germania Superior and Germania Inferior (Lower and upper Germany in the area along the river Rhine), Raetia,(central and eastern Switzerland, eastern Austria), Noricum (most of Austria, part of Bavaria and part of Slovenia), Pannonia Superior (eastern Austria and western Hungary), Pannonia Inferior (northern Croatia, Serbia and Bosnia & Herzegovina), Illyricum (the Rest of Bosnia & Herzegovina, coastal Croatia central Serbia, and Albania), Macedonia (northern and central Greece), Epirus(western Greece), Achaea (southern Greece), Thracia(northeaster Greece and eastern Bulgaria), Moesia superior(eastern Serbia and Macedonia) Moesia Inferior (most of Bulgaria), Dacia (Romania and Moldova), Asia (western Turkey), Bithynia et Pontus (northern Turkey), Galatia (central Turkey), Lycia et Pamphylia(southern Turkey), Cappadocia (eastern Turkey), Cilicia et Cyprus (Cyprus and the eastern part of the southern coast of Turkey), Corduene, Osroene ( both in northern Iraq), Syria Coele (Syria), Syria Phoenicia(Lebanon), Judaea (part of Israel), Arabia (Jordan, the Sinai peninsula and the northern part of the Arab coast on the Red Sea) Aegyptus (Egypt), ), Creta et Cyrenaica(Crete and eastern Libya), Africa (western Libya and Tunisia), Numidia (coastal Algeria), Mauretania Tingitana and Mauretania Caesariensis (both in northern Morocco).

Emperor Diocletian (reigned 284 to 305 AD) subdivided the provinces, creating a total of 122 provinces.

Marius fought several wars. He led the Romans in the Jugurthine War against Jugurtha, a usurper king of Numidia (in present day Algeria). He fought in the later stages of the Cimbrian War and defeated the Cimbri and the Teutones. These two migrating Germanic peoples had routed the Roman army once in Noricum (in present day Austria) and three times in Gaul. Tens of thousands of Roman soldier were killed. Marius defeated the Teutones and their allies, the Ambones, at the Battle of Aquae Sextiae (in Gaul). The Teutones and the Ambrones were virtually wiped out. He then defeated the Cimbri who were marching into Italy at the Battle of Vercellae (in Italy). He was also one of the Roman commanders in the War of the Allies (or Social War) in which Rome's Italian allies rebelled and fought against her.

Marius fought two civil wars against another Roman general, Lucius Cornelius Sula (they are called Sulla's First Civil War, and Sulla's Second Civil War). In the first occasion, Sulla was a consul and was assigned to lead the army in a war in the East. Marius persuaded, Suplicius, a plebeian tribune, to revoke the senate's assignment of command to Sulla. Suplicius also tried to get the assembly to expel senators until there were not enough senators to form a quorum in the senate. An attempt by thugs hired by the senators to kill Suplicius was foiled. Riots broke out in the city. Sulla fled Rome levied loyal troops and marched on Rome. This was unprecedented. Roman religion forbade bearing weapons inside the city walls. Sulla's senatorial officers refused to enter the city. Marius' supporters organised a force of gladiators to put up resistance, but Sulla's soldiers defeated them. Marius fled to Africa. When Sulla left to fight the war in the East, Marius returned to Rome. Together with his son and Cinna he seized control of Rome from Sulla's supporters and their leaders were killed. Marius declared Sulla's reforms invalid, had Cinna elected as consul and himself as commander of the war in the East. However, Marius died two week later and Cinna became in sole control in Rome. Sulla returned to Rome with his troops and surrounded the city. The people opened the gates and Sulla took the city without a fight.

Marius and Sulla were leaders of the pulularis and optimate factions respectively. The pupularis championed the cause of the poor and wanted reforms to help the poor. The optimates favoured the interests of the aristocracy and was opposed to the reforms. The conflict between these two factions continued and led to more civil wars and contributed to the fall of the Roman Republic. Marius was regarded as a hero by subsequent generations of the popularis.

Marius was elected as consul in 107 BC (the year of his military reforms). The consuls were the two annually elected heads of the republic and the army. He was elected again for five consecutive years because of military emergencies.

During the Late Republic the provinces of the Roman Empire were:

Sicilia

(Sicily), Corsica et Sardinia, Gallia Cisalpina(northern Italy), Gallia Narbonensis (southern France), Hispania Ulterior (Iberian peninsula), Hispania Citerior and Illyricum (the eastern coast of the Adriatic Sea), Macedonia (Greece), Asia (in western Turkey), Bithynia et Pontus (northern Turkey), Cilicia et Cyprus (Cyprus and the eastern part of the southern coast of Turkey), Bithynia et Pontus (in northern Turkey), Corduene (in northen Iraq), Creta et Cyrenaica (Crete and eastern Libya), Syria and Africa (western Libya, Tunisia, coastal Algeria and northern Morocco)

During the Principate, the period from the rule of Augustus to the Rule of Numerian (27 BC to 284 AD) the provinces of the Roman Empire were:

Sicilia

(Sicily), Corsica et Sardinia, Gallia Cisalpina (northern Italy), Britannia Superior

(northern England and southern Scotland), Britannia Inferior (Wales and central and southern England), Hispania Citerior (eastern Spain), Hispania Ulterior (northern and central Spain), Hispania Baetica (southern Spain), Lusitania (Portugal and part of eastern Spain), Gallia Aquitania (southeastern France), Alpes Maritimae, Alpes Poeninae and Alpes Cottiae, (the Alpine areas of southeastern France), Gallia Belgica (Belgium), Gallia Lugdunensis (central and northern France), Germania Superior and Germania Inferior (Lower and upper Germany in the area along the river Rhine), Raetia,(central and eastern Switzerland, eastern Austria), Noricum (most of Austria, part of Bavaria and part of Slovenia), Pannonia Superior (eastern Austria and western Hungary), Pannonia Inferior (northern Croatia, Serbia and Bosnia & Herzegovina), Illyricum (the Rest of Bosnia & Herzegovina, coastal Croatia central Serbia, and Albania), Macedonia (northern and central Greece), Epirus(western Greece), Achaea (southern Greece), Thracia(northeaster Greece and eastern Bulgaria), Moesia superior(eastern Serbia and Macedonia) Moesia Inferior (most of Bulgaria), Dacia (Romania and Moldova), Asia (western Turkey), Bithynia et Pontus (northern Turkey), Galatia (central Turkey), Lycia et Pamphylia(southern Turkey), Cappadocia (eastern Turkey), Cilicia et Cyprus (Cyprus and the eastern part of the southern coast of Turkey), Corduene, Osroene ( both in northern Iraq), Syria Coele (Syria), Syria Phoenicia (Lebanon), Judaea (part of Israel), Arabia (Jordan, the Sinai peninsula and the northern part of the Arab coast on the Red Sea) Aegyptus (Egypt), ), Creta et Cyrenaica (Crete and eastern Libya), Africa (western Libya and Tunisia), Numidia (coastal Algeria), Mauretania Tingitana and Mauretania Caesariensis (both in northern Morocco).

Emperor Diocletian (reigned 284 to 305 AD) subdivided the provinces, creating a total of 122 provinces.

Rome's expansion was very gradual and occurred over some 450 years. Its reasons varied from time to time. It was mostly due to military success. Rome fought and won many wars which occurred at different times and for different reasons. It was not the result of a grand design of imperial expansion. Rather, Rome, during the period of the Roman Republic stumbled on finding herself with an empire and was ill equipped to deal with this. It eventually fell under the weight of Imperialism and was replaced by the absolute rule by emperors.

The efficiency of the Roman army was an important factor in Rome's military success. Another important factor was Rome's alliances. When Rome gained control over most of central Italy and part of southern Italy by defeating the Samnites of southern Italy in the Three Samnite Wars ((343- 341 BC, 326- 304 BC and 298-290 BC), many peoples in this area made alliances with Rome, a few of them were annexed and the Samnites were forced into an alliance. The allies had to supply soldiers for Rome at their expense. The system worked because Rome supported the ruling elites and she shared the spoils of war, which could be considerable. Moreover, she fought to protect her allies. The allies provided at least 60% of the pool of military manpower available to Rome. This amounted to what has probably the largest military pool in the Mediterranean. Therefore, strength in numbers was an important factor.

Rome took over the Greek city-states of the heel and toe of Italy as a result of defeating an attempt to invade Italy by the Greek king Pyrrhus in the Pyrrhic War (275-270 BC). Rome won the Three Punic Wars against Carthage (264-241 BC, 218-201 BC and 149-146 BC). After the first was Rome Sicily, Sardiniaand Corsicafrom the Carthaginians. In the second war they defeated the Carthaginians in Spain and took over their territory in southern Spain. The Romans annexed this and eastern Spain as Roman provinces in 197 BC, On the third war Rome destroyed Carthage and seized her home territory, Tunisia and eastern Libya. The Romans also turned Illyricum(on the eastern coast of the Adriatic Sea) into a client with the Three Illyrian Wars (229/28 BC, 219 BC and 168 BC).

Rome fought a war against the Seleucid Empire (Roman-Seleucid War, 199-198 BC) and won. The Seleucids lost their territories in what is now Turkey. Rome gave many of these territories to the (Greek Kingdom of Pergamon (in western Turkey), which was an ally of Rome. She defeated the Galatians (Galatian War, 189 BC) and turned Galatia(in central Turkey) into a client kingdom. Cappadocia(also in central Turkey) became an ally of Rome. In 146 BC, after having fought several wars in Greece to help Greek states allied to her, Rome annexed mainland Greece. In 133 BC the last king of Pergamonbequeathed his kingdom to Rome. In 74 BC the last king of Bithynia(in north-western Turkey), who was also a Roman ally, did the same. The Romans fought the Third Mithridatic War (73-63 BC) against the Kingdom of Pontus(in north-eastern Turkey and its ally, Armenia. Rome won and annexed the eastern part of this kingdom and merged it with Bithynia. She turned Armeniainto a client state. In the same year (63 BC) she annexed Syriaand turned Judeainto a client state.

In the 120s BC Massalia (Marseilles), a Greek city in southern France which was a Roman ally, was attacked by Gallic tribes. Rome intervened and annexed southern France as the province of Gallia Narbonensis in 121 BC. In 58-50 BC there were the Gallic Wars in which Julius Caesar set out to conquer Gaul (France, Belgium, Holland south of the River Rhine and Germany west of the Rhine). This is the first instance of a deliberate conquest.

Augustus, the first Roman emperor, completed the conquest of central and western Spain, a process which was the result of local fighting against the Romans and losing their wars, in the last of such wars (CantabrianWars, 29-19 BC). In 15 BC he conquered Rhaetia(eastern Switzerland and part of southern Germany) because he considered this Alpine area as a buffer for the defence of Italy. He annexed Judeaon the request of the local Jews who were fed up with the misrule of the Herodian dynasty. He also set out to conquer the interior of Illyria, which led to the Great Illyrian Revolt (6-9 AD). The Romans also intervened in Moesia (central and eastern Bulgaria) to help an allied tribe for an attack. Moesia was joined into a military district together with Macedonia. They also conducted operations in Thrace(in south-eastern Bulgaria and north-western Greece) and turned it into a client kingdom. In 16 BC he annexed Noricum(most of Austria and part of Slovenia) because it had joined a raid on Italy by their neighbours. Under Augustus successor, Tiberius, Illyricum was divided into Dalmatia and Pannonia and the Moesia was separated from Macedonia as a province. In 6 BC Augustus promoted the conquest of GermaniaMagna(central Germany. By 6 BC the Romans had advanced to the River Elbe. However, three Roman legions were slaughtered by an alliance of Germanic tribes at the Battle of the Teutoburg Forest in 9 AD. This led to the Romans withdrawing from this area.

Only two other emperors carried out further conquests: Claudius and Trajan. Claudius ordered the conquest of southern Britain in 46. It is thought that he did this to bolster his political position in Rome, which was week. Vespasian ordered the conquest on Northern England because of a rebellion there. He annexed the client states of Lycia and Pamphylia (in Turkey), Thrace, Noricum and Mauretania (northern Morocco). Trajan waged war against the Dacians who were raiding the empire and conquered Dacia (part of Romania). He then fought a war with the Persians and conquered Mesopotamia(Iraq). His successor Hadrian gave Mesopotamia back to the Persians. After this there were not any further conquests.

The Celts inhabited large parts of Western Europe and the Romans beat scores of Celtic groups in northern Italy, France, Belgium, Spain, Switzerland, Austria and Britain.There were the Gauls of Gallia Cisalpina (northern Italy) and Gallia Cisalpina (France and Belgium), the Celtiberians of Spain and Portugal, the Celts of Rhaetia (eastern and central Switzerland, part of southern Germany, eastern Austria, and part of Lombardy, in Italy) Noricum (most of Austria and part of Slovenia) and Britain.

The Celts were generally treated well, like all the other conquered peoples, except for the rebellious Jews. Rome kept such a large empire unified through tolerance, legal protections, proving benefits, and propaganda.

The Romans tolerated the religions and customs of the conquered peoples. They allowed them to continue to worship their religions, follow their customs and use their customary laws at the local level. They also let the local ruling classes run most of the local affairs. The role of the provincial governors of the provinces (conquered territories) was restricted to defence and maintenance of the legions stationed in the provinces, tax collection, public works and the arbitration of disputes the locals could not resolve by themselves. This policy had two advantages: it reduced the administrative load of the provincial governors and it facilitated the integration of the locals into the ideology and the economy of the empire. A less tolerant policy would have led to too many rebellions and would have threatened the stability of the empire.

In 225 BC the emperor Caracalla extended full Roman citizenship to all the freeborn in the Roman Empire. Prior to this, the provincials, the people outside Italy who had been conquered or were under Roman influence, enjoyed the rights of jus gentium (the law of nations). Nation in the Latin was the word for ethnicity and just gentium was a sort of natural law which was regarded as "innate in every human being." The rights it conferred were considered to be held by all persons. They were based on the notion that the concept of justice sprung from the natural reason of the human mind rather than ethnicity and that they applied regardless of citizenship. Through this, the provincials enjoyed the protection of Roman civil law in their dealings with Roman citizens. Cases between Romans and non-Romans were adjudicated by the praetor peregrino, the chief justice for foreigners, who was supposed base his rulings on fairness and on Roman civil law.

Being part of the empire also provided economic benefits and, sometimes, security. The empire developed thriving trading networks and the Romans encouraged the peoples in the provinces to increase the production of manufactures agricultural goods for trade. The wealthy and middling class benefitted from this. The exploited poor did not. The Roman legions stationed in the provinces helped with maintaining order. In the frontier areas they also provided protection from raids from across the border. The troops were also customers for local traders.

The Romans fostered an imperial ideology to help to promote as sense of affinity and uniformity among the peoples in the empire.