THE JUNGLE IS NEUTRAL makes The Bridge Over the River Kwai look like a tussle in a schoolyard. F. SPENCER CHAPMAN, the book's unflappable author, narrates with typical British aplomb an amazing tale of four years spent as a guerrilla in the jungle, haranguing the Japanese in occupied Malaysia. Traveling sometimes by bicycle and motorcycle, rarely by truck, and mainly in dugouts, on foot, and often on his belly through the jungle muck, Chapman recruits...