Master and Commander, Patrick O'Brian. 1970.
Since I enjoy space opera, I've been told many times I need to read this series, since, really, space opera is a riff on the Age of Sail (in space!). After giving David Drake's futuristic take on this source a go, I thought I'd give this a try.
Captain Jack Aubrey, British Navy, meets Stephen Maturin, a doctor and naturalist, and persuades him to join his ship as its surgeon. They sail through the Mediterranean a lot and fight the French (and maybe also the Spanish? I was never very clear on that, and the whole Napoleonic Era is largely skipped in US high school curricula). There's also a subplot about the Irish Catholic rebellion.
I'd been warned about the quantity of ship-talk, but, man, that was more than I expected. There were entire pages I had no idea what was going on, except they were talking about topsails, mainsails, gallants, topgallants, royals, studdingsails, staysails, masts, yards, xebecs, snows, sloops, frigates, and cannons. "Oh, they're doing something with the ship again," was basically my take-away from it. That was fine when all they were doing was setting the rigging, but when it was important to what was going on, like during the naval battles, the result is just confusion. The only time I understood what was going on was when Jack was explaining in normal-people language to Stephen.
It's meticulously researched and written in meticulous 1810-era British navy slang and jargon. If you can handle that sort of thing, have at it. I find that it's too hard to wade through, honestly. Needs more spaceships.