Blood was shed, but mostly Vernon’s, because the retired chess club teacher kept his cool, gave his class an avenue of flight and remembered the knife-fight training the Army gave him five decades ago.

Vernon, 75, won his “90 seconds of combat” with Brown, “but I felt like I lost the war,” he chuckled. He cut two arteries and a tendon on Vernon’s left hand as Vernon blocked Brown’s knife swipe.

“I failed my mission to kill everyone,” Brown told police, according to a prosecutor’s court affidavit that accompanied formal charges Thursday that included attempted murder.