The WWI Battle of Jutland was the first, and only, large scale battle between the massive dreadnought battleships that had come to exist in 1906. There were other clashes of them, but none on this scale.
HMS Dreadnought, when built in 1906, immediately made all previous battleships obsolete. Her existence set off a massive naval arms race that involved the British Commonwealth, America, Germany, Austria-Hungary, Spain, France, Japan, the Ottoman Empire, Russia, Italy, Brazil, Argentina, and Chile.
On the night of May 30th-31st, 1916, both the German and British battle fleets left harbor, each thinking they were luring the other into a trap. All together there were 250 ships, carrying 105,000 men, on a collision course. Surprisingly, both fleets almost missed each other, and the battle was started by a small Danish freighter innocently blundering between them. Both sides sent small ships to investigate her, which sighted each other.
The battle raged on & off into night and early morning. When it was over 25 ships of various types had been sunk and 8,645 men killed. Although these losses were small compared to the terrible land war being fought in France, they were shocking for naval combat. And the battle, surprisingly, changed very little. Germany won a tactical victory, but the overall strategic victory went to Britain. The course of WWI hadn't changed.
And that's my summary. For those who want to learn more, I recommend watching this. Otherwise, just skip to the next paragraph.
The flagship of the British battlecruiser fleet was HMS Lion, led by Vice Admiral David Beatty. It was his division that had the first main contact with the Germans.
On board Lion was Major Francis Harvey of the Royal Marines. Born in Kent to a family with a long military tradition, he joined the navy at age 14. There he was quickly recognized for his proficiency in languages, gunnery, and debate.
He worked his way up through a series of ships, eventually becoming a gunnery instructor and in charge of training the crews of the navy's Channel Fleet. When World War I started, he was assigned to Lion, commanding one of her main gun turrets.
At Jutland, midway through the battle, Lion was hit several times by Admiral Hipper's flagship Lutzow. One shell penetrated the armor of Harvey's turret and exploded inside. The result blew the roof & front off the turret, killed or seriously wounded every man inside, and set fire to the bags of cordite explosive that were being readied for the next round.
Harvey was still alive. He'd had both his legs blown off, and was losing blood rapidly. Death was coming quickly. But he saw that the hatch separating the turret from the ammunition magazine below was jammed open by a piece of metal. When the burning cordite exploded the fire would spread down into the magazine and destroy the entire ship.
He dragged himself to the speaking tube and ordered the magazines below him flooded with sea water. When the fire did indeed spread a moment later, the ship was saved by his action.
The order was issued with Harvey's last breath. Immediately after giving it he collapsed dead.
Winston Churchill later wrote "In the long, rough, glorious history of the Royal Marines there is no name and no deed which in its character and consequences ranks above this."
Harvey was posthumously awarded his country's highest decoration, the Victoria Cross. His wife and son received the medal from King George V at Buckingham Palace. In 1973 his son loaned it to the Royal Marines Museum, where it can be seen today.
Harvey himself was buried at sea the day after the battle. His name is inscribed at the Chatham Naval Memorial. He was 43.