In mafia parlance, IRGC-QF Major General Qassem Soleimani's assassination "crossed a line" with the Iranians. During WWII, General George Patton was a High Value Target (HVT) and legitimate target of the enemy, like General Erwin Rommel was an HVT for the Allies. But had "Old Blood and Guts" been assassinated by Nazi resistance fighters after the war ended (AKA the "Werewolves"), the American public would have been pissed and called for their blood. The US was not in a Congressionally-declared war with Iran when Trumpf, in true mafia form, ordered the hit on MG Soleimani (who was a beloved hero and effective anti-ISIS commander). As we'd be pissed if someone took a shot at Obama, the Iranians are pissed that Trumpf and the neo-cons whacked Soleimani.

You need a citation that the 1945 American public would have been pissed if Patton was assassinated?

The American people adored "Old Blood and Guts." The Los Angeles Coliseum was packed to the gills in June 1945 to see him and General Doolittle. Here is General Patton being honored with a paper confetti parade.