Cover art
Turtledove, Harry, and L. Sprague de Camp. The Pugnacious Peacemaker / The Wheels of If (Tor SF Double #20). Tor 1990.

De Camp, L. Sprague. "The Wheels of If"
Divergence: 664 CE
What if: Oswiu of Northumbria adopted the Celtic rather than Roman branch of Christianity. Later, the Arabs won at Tours.
Summary: A district attorney from our New York finds himself residing in the body of a Celtic Christian bishop in "New Belfast".
Series note: Sequel is Harry Turtledove's "The Pugnacious Peacemaker".
Published: In Unknown, October 1940; The Wheels of If, Shasta 1948; The Wheels of If and Other Science-Fiction, Berkley/Medallion 1970 (0425018938); The Virgin and the Wheels, Popular Library 1976; Alternative Histories: Eleven Stories of the World as It Might Have Been (eds. Charles G. Waugh and Martin H. Greenberg), q.v.; The Pugnacious Peacemaker / The Wheels of If (Tor SF Double #20), Tor 1990 (0812502027); Unknown Worlds: Tales from Beyond (ed. Stanley Schmidt), Bristol Park 1993 (0884860779), Galahad 1996 (0883657287BUY); Down in the Bottomlands and Other Places (with Harry Turtledove), Baen 1999 (0671578359BUY); and Years in the Making: The Time-Travel Stories of L. Sprague de Camp (ed. Mark L. Olson), NESFA 2005 (1886778477BUY).

Turtledove, Harry. "The Pugnacious Peacemaker"
Divergence: 664 CE
Summary: Now a judge of an international court, the bishop is sent to South America to adjudicate a territorial dispute between the Incas and the Muslim Amazon.
Series note: Sequel to de Camp's "The Wheels of If".
Published: In The Pugnacious Peacemaker / The Wheels of If (Tor SF Double #20), Tor 1990 (0812502027); Down in the Bottomlands and Other Places (with L. Sprague de Camp), Baen 1999 (0671578359BUY); and We Install and Other Stories, Open Road 2015 (1504009428BUY).