The Three Block War is a concept described by U.S. Marine General Charles Krulak in the late 1990s to illustrate the complex spectrum of challenges likely to be faced by Marines on the modern battlefield. In Krulak's example, Marines may be required to conduct full-scale military action, peacekeeping operations and humanitarian aid within the space of three contiguous city blocks. The thrust of the concept is that modern militaries must be trained to operate in all three conditions simultaneously, and that to do so, leadership training at the lowest levels needs to be high. The latter condition caused Krulak to invoke what he called "strategic corporals"; low-level unit leaders able to take independent action and make major decisions.
The term has been referenced by then-CENTCOM commander (later Secretary of Defense) General James Mattis, and has also been adopted by the British, Israeli and Singaporean military, including former Chief of the General Staff, General Sir Mike Jackson and former Defence Secretary Geoff Hoon,[1] and also by former Canadian Chief of Defence Staff Rick Hillier.[2]