...where one side was expected to allow the other side to be supplied.

Like, the Germans in World War I were supposed to say "People in England are starving. We better call back our U-boats."

Or when the Allies had Sevastopol besieged during the Crimean War saying "We're trying to get the City to surrender. Let's send the residents food."

Or when the Boxers had Peking besieged saying "Ya know what will get the Allies to surrender? If we send them food."

It's a war. War is cruelty, and cannot be refined.