He returned to Germany at the end of the war and studied philosophy and theology in Bonn, particularly under Friedrich Nötscher and Heinrich Joseph Vogels.
In 1946 he entered the community at Maria Laach Abbey under abbot Ildefons Herwegen and received the religious name Anno.
On August 24, 1948, he took his first monastic vows and in 1952 he was ordained a priest,[1] becoming chief assistant to novice master Basilius Ebel.
On 4 November 1990 he succeeded Adalbert Kurzeja OSB (born 1920) when he was elected 48th abbot of Maria Laach Abbey.
Schoenen was strongly influenced by Rudolf Tippmann and E. Nüßlein, who had taught him pastoral studies, liturgy and religion at Essen, and by Max Josef Metzger.