American occupations of Germany and Japan
The most striking fact about them I think is that they began during a rapid demobilization of the U.S. military. The U.S. Army (which included the Air Force at the time) shed 7 million troops in a little under 2 years.
U.S. Army strength:
Summer 1945 - 8 million
End of 1945 - 4 million
Summer of 1946 - 2 million
Summer of 1947 - less than 1 million
Another interesting point is that they were quite unpopular.
Not only was President Truman under pressure from Congress and the American people to "Bring the Boys Home," but in the summer of 1946, when the troops still waiting to be shipped home were informed that they were being kept to participate in the occupations, riots broke out at many U.S. bases around the world. Truman had to relent and continue the demobilization.
The two occupations were quite different. The Japanese government was kept largely intact while their constitution was written and members of parliament elected. Germany was much more like Iraq, where the government was de-nazified and then restaffed over many years.
In both cases, though, they went quite smoothly. It was the rise of Soviet (and later plus Chinese) Communist spheres of influence that forced the conversion of the relatively lax occupation forces into defensive forces by early 1948.
By 1950, the U.S. Air Force had split from the Army and the Army itself was left with a troop strength of 592,000 volunteers. Roughly half of them were stationed in Germany and Japan (100,000 in Germany, 130,000 in Japan).
Country populations - 1950:
U.S.A - 158 million
Japan - 84 million
W. Germany - 50 million
The Soviet and U.S. spheres of influence were established, leaving divided Korea in a no-man's land with only a few Soviet and American advisors in their respective halves. When the North Koreans invaded South Korea, the U.S. forces occupying Japan were sent to support the South Koreans.
Our occupation forces in Germany and Japan grew rapidly during the Korean War. After the Korean War, the number of troops stationed in Japan steadily declined from a peak of 220,00 to about 50,000 today. Troop numbers in Germany remained at about 250,000 until the end of the Cold War in the early 1990s then fell rapidly to about 60,000.
It's hard to find comparisons between America's post-WWII occcupations of Japan and Germany and our current occupations of Iraq and Afghanistan.
The German and Japanese occupations met with little resistance. They weren't popular domestically. And they were soon overshadowed by the beginning of the Cold War.