People can't seem to differentiate the First and Second Wars.... is this lie still flying around? The British propaganda machine largely manufactured that to demonize the Germans. Remember, the Germans were the ones that built the rules of war framework, and the Germans in WW1 were still within that framework. This was why everyone not on the Eastern Front was flabbergasted at the Holocaust during WW2.
In the First, Germany was just like every other country fighting -- hell, their motivations were so uniform that you could just swap the flags around at random and they'd still apply to that swapped country! They weren't evil monsters, and if they are considered monsters by people too dumb enough to understand context, then everyone else --the British, the French, the Italians, the Russians, the Japanese, et cetera-- would've been monsters too by their standards.
Except the Americans -- they came in way too late, did fuck all, and still had the gall to demand a seat at the negotiating table, so they were pretty irrelevant.
The Second World War, however... that was a completely different beast. Mass war crimes, especially by Germany and Japan and (near the end of the War) Russia (Berlin; 'nuff said), organized and industrialized genocides, et cetera.
That's the War when the monsters emerged.