Many critics of the Crusades would seem to suppose that after the Muslims had overrun a major portion of Christendom, they should have been ignored or forgiven; suggestions have been made about turning the other cheek. This outlook is certainly unrealistic and probably insincere. Not only had the Byzantines lost most of their empire; the enemy was at their gates. And the loss of Spain, Sicily, and southern Italy, as well as a host of Mediterranean islands, was bitterly resented in Europe. Hence, as British historian Derek Lomax (1933-1992) explained, 'The popes, like most Christians, believed war against the Muslims to be justified partly because the latter had usurped by force lands which once belonged to Christians and partly because they abused the Christians over whom they ruled and such Christian lands as they could raid for slaves, plunder and the joys of destruction.' It was time to strike back.