A quote from LifeSite News, 3 April 2008
In December, Catholic author Frank M. Rega released Francis of Assisi and the Conversion of the Muslims; With Concise Biography of the Saint, a book that has received much praise for its biographical portrait of the renowned saint and its highly pertinent focus on St. Francis's relationship with Muslims of the time.
During the Fifth Crusade to Egypt, St. Francis of Assisi walked into a Muslim camp in order to preach Christianity and convert the sultan. Rega's new book recounts St. Francis's bold encounter with the sultan and other important events from the life of the man from Assisi some claim more closely imitated Jesus Christ than any other saint in history. […]
LifeSiteNews: Why did St. Francis of Assisi support the Fifth Crusade?
Frank Rega: Francis understood that the Fifth Crusade was part of an ongoing just war in response to Muslim invasions of Christian lands, which included many attacks against Italian city-states all along the peninsula over the course of centuries. For example, in the year 846, Rome itself was sacked by 11,000 Muslims, who desecrated the tombs of Sts. Peter and Paul.