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On May 27, 1941, the German battleship Bismarck was sunk in the North Atlantic by the British Royal Navy after an intense multi-day pursuit. The Bismarck, the largest battleship built to that point, had sunk the battlecruiser HMS Hood three days earlier, killing 1,418 sailors. The sinking of the Bismarck, with 2,092 dead out of 2,221 crew, was the greatest loss of the German Navy.

On May 27, 1564, French Protestant reformer John Calvin died in Geneva — whose theology — Calvinism — profoundly influenced the development of Protestantism in Switzerland, France, Scotland, the Netherlands and North America. The Protestant ethic described by Max Weber in his 1905 work was based primarily on Calvin's ideas about work, saving and predestination.

On May 27, 1905, the Russian Pacific fleet was destroyed by the Japanese navy at the Battle of Tsushima — the greatest naval disaster since Trafalgar. Japan destroyed 21 of the 28 Russian warships while losing only 3 torpedo boats. The Japanese victory, the first by an Asian nation over a European power in the modern era, shook the world and forced Russia to sign peace. The defeat discredited the tsarist government.