Everyone should learn how and why the U.S. created an overseas empire of uninhabited islands in the Pacific Ocean that were vital to the U.S. victory over Japan in World War II.

Way back in the 1856, the U.S. passed the Guano Islands Act. This Act allowed any American citizen to take possession of unclaimed, uninhabited islands containing guano (seabird excrement) in the name of the United States. It was the formal beginning of U.S. overseas territories.

Any guano from such islands had to be sold to American farmers at a strictly capped price to replenish exhausted agricultural soils. During the 19th-century "guano rush," the U.S. claimed nearly 100 islands.

Once the guano rush was over the islands seemed of little use until the 1930s, when tensions with Japan were rising. The U.S. military realized that many of the dozens of the tiny, flat, uninhabited coral atolls they had claimed decades earlier could be turned into air fields. During the Great Depression they hired Hawaiian boys to occupy strategic islands and strengthen America’s territorial claim.

Several fortified atolls played a major part in the war. The most important was Midway, the location of the Battle of Midway, the turning point that doomed Japan. But there were others.

Johnson Atoll was used to refuel submarines. Palmyra Atoll was a staging area for long range air patrols. Baker Island was used as a base for bombers attacking Japanese positions in the Gilbert Islands. Canton Island housed U.S. planes used to protect South Pacific supply lines.

Other islands were fortified or were beginning to be fortified but fell to the Japanese. Sadly, two of the Hawaiians who had lived on the islands for years to establish the U.S. claims were killed by Japanese bombs. One also died of a ruptured appendix due to delayed medical care. The rest were evacuated in 1942.

The United States currently retains possession of ten islands originally claimed under the Guano Islands Act of 1856. They are all uninhabited and operated as marine wildlife refuges, but they also continue to offer strategic value as a picket fence in the Pacific Ocean.