Troops have long used animals in warfare. Horses to carry them into battle, pigeons to send messages, and dogs to do all sorts of things a good boy does. The Animal Kingdom's second smartest species is no exception when it comes to fighting in our wars.
The military dolphin program began in 1960 when the U.S. Navy was looking for an easier method of detecting underwater mines. Their solution was to use the animals that play around the mines without problem: the bottlenose dolphin and the California sea lion.
Dolphins are naturally very brilliant animals with an advanced memory and strong deductive reasoning skills. Their ability to understand that performing certain tasks meant getting fishy treats allowed the U.S. Navy to make excellent use of their biosonar. Every mine they locate, they get a treat. Sea lions are just easy to train and have good underwater vision. According to the Space and Naval Warfare Systems Command, there are roughly 75 dolphins and 50 sea lions in the Navy Marine Mammal Program.
Military dolphins have many unique abilities to offer the Navy if trained properly. Outside of mine detection, they make excellent underwater guards. Dolphins can be trained to distinguish friendly ships from foes and, when a threat is detected, will press an alert button on allied posts.
With further training, dolphins can actually place mines on the bottom of ships or physically attack enemy divers.
Since the program began, dolphins have been used in every conflict alongside the Navy. In Vietnam, they were used to guard an ammunition pier. In the Tanker War, the US protected Kuwaiti oil exports by deploying dolphins to guard Third Fleet ships.
Unfortunately, this hasn't come without harm to our porpoise partners. They're naturally playful animals and changing a normally cheerful animal into a beast of war, even if just for training, ruins the dolphin's chance at a normal life. They aren't meant for domestication and the added stress greatly reduces their life expectancy.
The U.S. Navy isn't the only nation to use military dolphins. Russia, Ukraine, and possibly Iran do as well and, sadly, their marine mammals aren't treated anywhere near as well. A scathing statement from Kiev about the Ukrainian dolphins that were taken by Russia after the annexation of Crimea supposedly applauded the deaths of the starved dolphins. To them, the dolphins were "so patriotic" that they would sooner die than follow Russian commands.