Short answers, pulled from the story.
The Six Ton Tank M1917 was the first American mass-produced tank, a license-built near-copy of the French Renault FT. The U.S. Army ordered approximately 4,440 between 1918 and 1919 but received only about 950 before canceling the contract; the first two did not arrive in France until the 20th of November 1918, nine days after the armistice.
Eisenhower established and commanded the Army's primary tank training center at Camp Colt in Gettysburg, Pennsylvania, during World War I. He rose to the temporary rank of lieutenant colonel in the National Army and trained crews there, at first using trucks with bolted-down machine guns because actual tanks had not yet arrived. From 1921 to 1922, he commanded the 67th Infantry (Tank) Regiment, which was equipped with Liberty tanks.
The National Defense Act of 1920 dissolved the Tank Corps as a separate branch and placed tanks under infantry control, which reduced funding and constrained design priorities. Weight limits imposed by the War Department made it nearly impossible to build vehicles that met operational requirements, and the Army's preoccupation with light infantry-support tanks slowed development of heavier vehicles.
The Army produced seven main sub-designations of the Sherman: M4, M4A1, M4A2, M4A3, M4A4, M4A5, and M4A6, manufactured concurrently at different plants. A limited run of 254 M4A3E2 Jumbo Shermans was accepted in June and July of 1944, featuring armor exceeding 7 inches in effective thickness at some points. The British produced over 2,000 Sherman Firefly variants mounting the Ordnance QF 17-pounder gun.
The M18 Hellcat was a 76 mm gun motor carriage used in the Italian, European, and Pacific theaters and in the Korean War. It was the fastest armored vehicle in the American defense inventory of the 20th century until the turboshaft-powered M1 Abrams appeared, achieved by limiting armor to no more than one inch and using a radial engine originally designed for aircraft.
The M46 Patton replaced the M26 Pershing's 500 hp engine with the Continental AV1790-3, rated at more than 800 hp, and added a more reliable Allison CD-850-1 cross-drive transmission. A total of 1,168 M46 tanks were manufactured between 1949 and 1951, and the first were deployed to South Korea on the 8th of August 1950. By the end of 1950, 200 M46 Pattons were in service, forming about 15 percent of U.S. tank strength in Korea.