Who was the pope that convened Vatican II?
Pope Pius IX convened the First Vatican Council which began in
1868.
Pope John XXIII convened the Second Vatican Council which began
in 1962.
Pope Paul VI reconvened the Second Vatican Council in 1963 after
it was suspended due to the death of Pope John.
Pope John had to close the First Vatican Council before opening
the Second Council since the First Council was never officially
closed by Pius, it ended abruptly, or temporarily suspended because
the Franco-Prussian War broke out and the bishops in attendance
wanted to return to their diocese. After Rome was captured, Pope
Pius permanently suspended the Council but did not close it
officially.
Pope John died during the intermission break between the first
and second session of the Second Council to which it was suspended.
Once Cardinal Giovanni Montini was elected as Pope Paul VI, he
reconvened the Second Council and presided over it until its ending
in 1965.