Part of the invaders of North Africa sailed direct from the U.S. Part used Britain as a way station. The two forces were segments of an army that in two years had grown tenfold and encircled the earth.
Back in November 1940 (France had fallen, Britain had staved off the Luftwaffe, Russia was neutral), the U.S. Regular Army numbered a pitiful 380,000 men, the National Guard 112,000. Then came conscription. As the army multiplied, so did its tasks.
Even before Pearl Harbor, part of the available forces (the Regular Army plus quickly trained recruits) had been doled out to these far-flung regions: