After the land grab following World War II, a vast sea of communist red splashed across Eastern Europe, all the way to the Arctic and Pacific Oceans.

Mao and Khrushchev during happier times in 1958

It stands to reason that under communist control, neighboring China and the USSR would get along like the United States and Canada -- bordering nations with a shared vision of government. This wasn't the case.

The two states fought over borders beginning in the 17th century during the reigns of the Romanoff czars and the Ming Dynasty. These tensions continued into the mid-20th century and finally boiled over into armed conflict in the spring of 1969. At the helm were Soviet Premier Nikita Khrushchev and China's Chairman Mao. While 4,500 miles (7,242 km) of the Sino-Soviet border between the nations were under dispute, it was a tiny island in the Ussuri River along China's eastern border with the USSR that led to bloodshed.