In 1927 he was assigned as memher of Menbere Leul Markos Church in the compound of the then Gennete Le’ul Imperial Palace at 6 Kilo where he became the spiritual father of Ras Tafari (later Emperor Haile Selassie).

One of his preaching was Colossians 3:12 "Therefore, as God’s chosen people, holy and dearly loved, clothe yourselves with compassion, kindness, humility, gentleness and patience."

Following the Italian victory at the Battle of Maychew, Ethiopian Patriots fold to areas in the south and Abune Petros went to the Monastery of Debre Libanos.

"[4] Bishop of Dessie at the end of the Ethiopian war he decided to support the nascent Ethiopian resistance and refused to submit to the Italian authorities, he then joined the arbegnoch of Aberra Kassa, one of the sons of Ras Kassa who directed the guerrilla warfare in Shoa.

At a meeting in Debre Libanos, with the presence of Aberra Kassa, Abebe Aregai and other leaders, a rash plan was decided to assault the capital with five separate columns, counting above all on exploiting a general uprising of the population.

[5] With the opportunities he had, Abune Petros preached both Ethiopians and Italian soldiers about "peace, love and freedom".

[6] Before his execution, the authorities gave him a final offer: if he ceases to denounce the Italian invasion and if he agrees to publicly condemn Ethiopian patriots, he would be released.

A memorial statue is erected in 1946 near St. George's Cathedral, Addis Ababa and the author Tsegaye Gebre-Medhin wrote a play on his last days.