In the winter of 1966, Mr. Sagi’s commanders sent him on a secret mission, via Israel’s then-ally, Iran, to aid Mullah Mustafa Barzani and his pesh merga rebels in Iraqi Kurdistan. Six Iraqi army brigades were standing by to overwhelm the Kurds when the snow melted. Mr. Sagi, a lieutenant colonel, drew up defenses for Barzani’s lightly armed fighters. When those collapsed, Mr. Sagi advised the Kurds to allow the best of the Iraqi brigades to break out — right into an ambush.