what was the prayer of saint francis about?
It is a widely known Christian prayer for peace.
Prayer of Saint Francis
 Prayer of Saint Francis (or Peace Prayer, or Simple Prayer for Peace, or Make Me an Instrument of Your Peace) is a widely known Christian prayer for peace. 
lord make me the channel of thy peace UNANSWERABLE
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Prayer of Saint Francis [SEP] Introduction
The anonymous text that is usually called the Prayer of Saint Francis (or Peace Prayer, or Simple Prayer for Peace, or Make Me an Instrument of Your Peace) is a widely known Christian prayer for peace. Often associated with the Italian Saint Francis of Assisi ( – 1226), but entirely absent from his writings, the prayer in its present form has not been traced back further than 1912. Its first known occurrence was in French, in a small spiritual magazine called "La Clochette" (The Little Bell), published by a Catholic Church organization in Paris named "La Ligue de la Sainte-Messe" (The League of the Holy Mass).