A succinct email reached me from California this week, which read as follows. “Two lessons from Vietnam: 1) Don’t go to war unless you intend to win. 2) Never underestimate your enemy in tenacity or resourcefulness, no matter how out-gunned.” This was from a guy called Mike Eiland, whom you may not have heard of. Nor are the names of Frank Scotton or Frank Snepp likely to ring bells.

Yet in their day all were US intelligence legends, men who spent years in Vietnam, where they tried to speak truth to power, work with the Vietnamese and help avoid the killing of too many people. I met them way back, when writing a book on the war. Their old timers’ group still copies me in on their email exchanges.