Aden, June 20, 1967: two army Land Rovers burn ferociously in the midday sun. The bodies of nine British soldiers litter the road. Bright flames mixed with thick, black smoke bellows above Crater town, a tough Arab neighborhood built on top of a dormant volcano. Surrounded by high rugged peaks and perched on the south-western edge of the Arabian peninsular, it is home to insurgents, terrorists, and gangsters, who establish "no-go areas" against the...