Is it true King Arthur was a real person, who profoundly influenced actual history? The evidence presented here comes from many reliable ancient sources depicting Britain around the year A.D. 500, and from numerous modern historians who have developed methods of examining ancient records to uncover hidden kernels of historical truth. Accepted history is compared with intriguing details imbedded in the Anglo-Saxon Chronicle and other legendary sources. The most valuable contribution is a careful study of major events in Gaul and Britain during the Arthurian era to show how a leader of Arthur's stature could have caused the known victories in battle and shifts in political power. Every major battle in which King Arthur supposedly engaged is treated as an actual happening and described in meticulous detail, complete with maps and campaign charts. What just a few years ago seemed a futile quest now is being taken seriously: that only a historical person who truly achieved greatness could have inspired such timeless legends.