Submarine (1917): Unrestricted & US entry

The submarine is a legal and logistic problem that became a deterrent -- told as history. U-boats, the Lusitania, and 1917 unrestricted war as a political hinge. Convoy was the reply that worked -- a historical sentence, not a present ASW manual. Q-ships and atrocity stories are part of the memory, not a technique list.

Donitz, Enigma, the "happy time," and the 1943 Atlantic turn. In the Pacific, US boats and mines closed Japan's economy. Tonnage is the honest unit of that campaign. Nautilus; then SSBNs (George Washington, Resolution, Red October-as-fiction). A quieter Cold War with collisions and close calls in the public record.

More states with boats; ROK KSS as an industrial-national chapter; accidents (Kursk 2000) as a civilian-memory shock. Still not a how-to. A legal weapon of 1917, a tonnage weapon of 1944, a deterrent of the 1960s. Unrestricted U-boat war as a political hinge. Atlantic and Pacific tonnage campaigns.