Even though we could look at World War I or World War II as a whole, and state that they were both bloody battles, we are looking more closely at individual battles that took place. So, when you bring things down to a narrower field, which battle is actually the bloodiest in not only history connected to either war, but in history in general?
The answer is the Battle of Stalingrad, and this was nothing more than an absolute massacre. Even though there are no exact numbers, it is accepted that there were a minimum of 800,000 casualties, and the figure may have actually been as high as 1.6 million. It must be noted that this is related solely to the number of casualties resulting directly from the war itself and not through normal disease, but it does show how nobody really wanted to fight this battle as the chances of coming out on the other side without injuries did appear to be relatively slim.