NEW STEP BY STEP MAP FOR UNDERWATER NUCLEAR TEST 'UMBRELLA' (1958)

With test moratoriums about the horizon, American weapons labs rushed out several new layouts. A hard deadline for testing was established at midnight (0000 hrs), 31 Oct 1958, as negotiations had been established to start out that working day, and also the program exhibits it, with 29 tests executed in October, four of these on the last working day