The Soviet T-54’s well-angled armor and 100 mm gun made it one of the most advanced tanks of its day. The NVA first unleashed its T-54s in February 1971, and they spearheaded its 1972 invasion of the South. A lack of experience with armor initially caused heavy losses—like this captured T-54 in April 1972—but the NVA learned its lesson, and tanks spearheaded its final offensive, when T-54 crewmen were the first to enter the Presidential Palace on April 30, 1975. (AP Photo/Nick Ut)