Those ships stopped every two days to refuel and replenish, though. A starship might slow down after five years.
Organia had nothing on its surface but mud huts (and, suddenly, a castle popped up when one was needed). A lot like the Pacific islands, then. But in the Trek scenario, importing a forward operating base would take more time than concluding the war! Indeed, island-hopping stretched what might have been a two-month war into one years long, as worthless islands were conquered even though the US could simply have ignored all of them and sailed all the way to, heck, Iwo Jima and swiftly built a forward operating base there that would dwarf Truk, Rabaul and the Greater Tokio Industrial Area put together. And this only because their ships didn't quite have the range to bombard Tokyo directly to submission with one sortie - unlike starships.
A better WWII comparison, then, would be the Germans landing in their gliders on top of the Eben-Emael fortress in the smashing surprise strike - and then digging in, carefully enslaving the fortress troops, and setting up camp for future stages of the campaign, all while the French and the BEF proceeded to win the war and march into Berlin.
How swift was the war? Well, the moment the negotiations broke down, Kirk's ship was surprised with her pantaloons down. She survived, and rushed at best possible speed to establish defenses at Organia, one of the many leaky parts of the border, those clearly being so numerous that Starfleet could only afford to send this one cruiser, rather than the "fleet" that later was sent - the expectation apparently being that Kirk would first talk with the locals to get permission, and Starfleet would next haul in some hardware. Well, the Klingons didn't oblige, but simply took the place while Kirk was still trying the preliminary niceties on the locals. It's really difficult to see them stopping there, then, and squandering their strategic surprise.
Timo Saloniemi