A hot and fetid June night on the small Mediterranean island of Malta, and a Christian sentry patrolling at the foot of a fort on the Grand Harbour had spotted something drifting in the water. The alarm was raised. More of these strange objects drifted into view, and men waded into the shallows to drag them to the shore. What they found horrified even these battle-weary veterans: wooden crosses pushed out by the enemy to float in the harbour, and crucified on each was the headless body of a Christian knight. This was psychological warfare at its most brutal, a...