The First Battle
One of the earliest observed battles in the Sea of Thieves is the fight between the crews of the Mermaid's Fortune, the Serpent's Lie, and the Mad Monkey.
Although it looked like the Mermaid's Fortune was going to win, the crews of the Serpent's Lie and Mad Monkey lured the former crew to drink with them. Whilst the crew of the Mermaid's Fortune was inebriated, the latter crews laid into the Mermaid's Fortune ship and sunk it. Those two crews then turned against each other and it is unknown who the victor was.
Tales From The Sea of Thieves