The film's villain is a British politician who wants to negotiate an end to the conflict, seeking "peace at any cost" ... that motherfucker. Wonder Woman and a time-displaced Captain Kirk ultimately reveal that signing an armistice would be a mistake, as General Ludendorff and his German troops have a secret plan to unleash a deadly gas. The Allies would be fools to even think about making peace ... at least, not until Germany is naught but rubble and corpses.
When Wonder Woman is stopped from murdering Ludendorff, it directly leads to him gassing the shit out of a quaint little village, killing hundreds of civilians. As an added bonus, it turns out that the peace-seeking politician is secretly an evil deity who only wants the armistice because he knows it would fail. He is in fact Ares, the Greek god of war and proud member of GWAR.
Warner Bros. Pictures
Within the context of the movie itself, Wonder Woman is totally justified in turning a few hundred Germans into poppy food. Ludendorff was evil, whatcha gonna do? But the filmmakers had total control over that universe and how they wrote it. They chose to make the guy who wants peace pure evil incarnate. If you made a movie where anti-Iraq-War protesters were all evil werewolves, then in-universe Sylvester Stallone would be totally right to throw them from a series of blimps. It's still hella weird that you made that movie, though.