"A guerrilla leader can be successful only in very special circumstances. For us, the circumstances had not been perfect, but they had certainly been good. First and foremost is terrain. Guerrillas need cover to operate effectively—mountains, forest, or jungle. ... On mountain and jungle trails, guerrillas on foot are as mobile as a motorized enemy. It was the terrain that made it possible for us to find safety in constant movement, rarely spending two nights in the same place."