James Chadwick

Chadwick came up through Manchester under Ernest Rutherford, spent World War I interned in Germany after getting caught mid-research, then followed Rutherford to Cambridge's Cavendish Laboratory in 1921. There he hunted the missing piece of atomic structure for over a decade, finally isolating the neutron in 1932 and measuring its mass soon after. The Nobel came in 1935; by 1941 he was drafting the MAUD Report that launched American bomb research in earnest. He led the British contingent on the Manhattan Project through the war, was knighted in 1945, and spent his final academic years at Liverpool turning a backwater lab into a nuclear physics hub with a shiny new cyclotron. He died in 1974, thirty years after the thing he'd imagined as a cancer treatment helped end a war.