When we think of "war mongers", I'm willing to predict that your immediate thoughts go toward the military, soldiers, generals, etc. But if you take a second to think about it, you'll quickly realize that the root of war isn't about those who fight these battles. Rather, it’s the politicians who instigate these conflicts. The most recent Iraq War was very much George W. Bush's, while Desert Storm was George Bush Sr's.
When I think of politics, I think of Americas two major political parties: The Republicans (whose mascot is the Elephant) and the Democrats (whose mascot is the Donkey)
Alighieri chose to immerse his warmongers in the Phlegethon, a boiling river of blood (the blood being sourced from the sinners victims). So, for this section of hell, I chose to stock the Phlegethon with Elephants and Donkeys.