The breed commonly referred to as "Devil Dog" is the Dobermann.
During World War II, the United States Marine Corps adopted the Dobermann Pinscher. Marines gave the breed this fearsome nickname in recognition of its courage, tenacity, and effectiveness in combat situations, particularly in the Pacific theater. The Dobermanns served as sentry dogs, messengers, and scouts, often tasked with flushing out enemy combatants. Their intimidating appearance and fierce loyalty further cemented the "Devil Dog" moniker. They became the official war dog of the USMC.
