One instance when dolphins almost (just almost) succeeded in ruling the world.
1. The American Revolution
Now for a while, the war was going on smoothly for humans. The history books may have told you that the war was the war that was fought for american revolution, but that is false. In fact, the name is a misnomer. The war was really the first instance where dolphins and humans fought. (There were a few breakouts in the 1300's, but the offenders were quickly tried and sentenced to being killed in order for humans to be able to eat tuna fish.) Dolphins wanted the right to be able to kill off any human over the age of 130. Now currently, even today there has not been reported cases of humans living past 120. So this seemed like a pretty good demand for the dolphins, this would not even happen for hundreds of years. But for some reason, humans didn't agree. One thing led to another, and dolphins and humans were at war.
How about a compromise? Anybody over 140 we get to rip into pieces.
Now you may be thinking, how did this escalate into dolphins almost taking over the world? Well, we will tell you (but only if you're good). The dolphin general, a distinguished Delphinidae Delphis by the name of Squeak whistle 4th, had just taken over Australia. With Siam also in control of the dolphins, and a good build up on India, the dolphins ranks were sure to get a +2 armies every turn (disregard this please, we were thinking of Risk). Anyway, with Australia controlled by the dolphins, the infinite supply of oil there (shhhhh, they won't tell us where it is) was easily harvested and used as fuel for their cars. Humans did not have cars then, as it was only the 1700's, so dolphins easily ran over humans like squirrels. Bit by bit, the dolphins managed to fight their way up to Europe, where they met the French army at Frenchytown. The French managed to blow up the main fighting force of the dolphins, The Happy Slaughterers, and also kill the dolphin's leader. However, Frenchytown was destroyed beyond recognition, and the French were forced to move their capital over to Paris, where they lived happily ever after. Later, seperate plans were found in the underground bunker of the dolphins, that revealed that a seperate commander and his troops were sent over to Kamchatka, the only place left in Asia that the dolphins hadn't completely destroyed. With Kamchatka theirs, the dolphins would have gotten +7 armies every turn (Sorry, still thinking of risk). Luckily, the seperate force was annihilated by a small angry cat. World saved, the humans went back to their daily lives and completely forgot about dolphin intelligence.