The US captured one of its most important military outposts from an enemy who didn’t even know it was at war

• In June 1898, the US Navy sailed to Guam to capture the island from the Spanish.
• The Spanish, who didn't know they were fighting the US, surrendered the island without a fight.
• Guam is still a US territory, and it now hosts some of the US's most important military bases.
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In eight months of fighting in 1898, the US secured its status as a global power by defeating Spain in the Spanish-American War.

Fought on two continents, the war had a number of important moments for the US military. It led to the independence of Cuba (with the US as the dominant power there) and to US control of Puerto Rico, the Philippines, and Guam.

While there were battles in both Puerto Rico and the Philippines, Guam was taken without a fight. Indeed, the Spanish on the island had no idea they were even at war.

An important stop

In the 1898, the big prize for Spain and the US in the Pacific was the Philippines. Guam was an important stop between the Americas and the Philippines, but neither Spain nor the US paid much attention to it.

The Americans had already positioned Commodore George Dewey's Asiatic Squadron off China in anticipation of striking the Spanish fleet at Manila. But after a May 9 meeting of the US Navy War Board, which was formed to develop a strategy for the war, it was decided that Guam should also be taken to support operations in the Philippines.

To seize it, Secretary of the Navy John Long issued sealed orders to Capt. Henry Glass of the USS Charleston, a protected cruiser en route from California to Manila.

In Honolulu, Charleston was joined by three troop transports. As instructed, Glass only read his orders after leaving Hawaii on June 4.

"You are hereby directed to stop at the Spanish Island of Guam," the orders read. "You will use such force as may be necessary to capture the port of Guam, making prisoners of the Governor and other officials, and any armed force that may be there."

Glass was also ordered to destroy any Spanish fortifications or naval vessels he encountered.

Complete surprise

Though the orders said the operation "should not occupy more than one or two days," Guam's defenses were not entirely known, so while en route Charleston's crew spent days firing on practice targets in the ocean.

Charleston arrived off Guam on the morning of June 20. Encountering only an abandoned fort and no Spanish ships in Agana, the capital city, Glass ordered his ship to sail to Apra Harbor.

To the crew's disappointment, the only vessel there was a Japanese trading ship. Charleston fired several shots at Fort Santa Cruz to see if it was occupied, but it was also abandoned.

Spanish officials soon sailed out to meet Charleston in two small boats, one of which had a US flag on its topsail.

Upon boarding the Charleston, the Spaniards apologized. They had interpreted Charleston's gunfire as a salute, and they told the Americans they could not respond in kind because of a lack of gunpowder.

It turned out the island hadn't communicated with Manila since April 14 - 11 days before the US declared war on Spain - and no Spanish Navy vessel had visited Guam in 18 months.

Glass told the Spaniards that their countries were at war and that he was taking over the island. He demanded Guam's governor, Don Juan Marina, surrender the island in person aboard Charleston.

The delegation returned, and Marina requested to speak to Glass on the island instead, as he was not legally allowed to board a foreign warship.

The next day, Glass sent an envoy to demand the Spanish surrender and gave them a half-hour to comply. Twenty-nine minutes later, Marina surrendered.

The island's garrison, which had fewer than 60 men, was disarmed and taken as prisoners aboard one of the transport ships, as were Marina and other Spanish officials.

The Americans then set sail for Manila, where they assisted Dewey for the rest of the war.

An important base

After the surrender, Glass personally examined Fort Santa Cruz, where he raised the American flag.

The fort itself "was entirely useless as a defensive work, with no guns and in a partly ruinous condition," Glass wrote in a report to Long.

Glass described the other forts on the island as having "no value," and that the only guns that could be found were obsolete cast-iron guns used for saluting "but now condemned as unsafe even for that purpose."

While the Spanish had neglected Guam, the US turned it into an important base.

The Japanese captured it on December 10, 1941, but the US retook it in a bloody 21-day battle in summer 1944, and used it as a base for B-29 bombing missions for the rest of the war.

Guam is now home to roughly 170,000 people, and its importance for the US military has only increased.

It is now the US's "most critical operating location west of the international dateline," Adm. Philip Davidson said before retiring as head of US Indo-Pacific Command earlier this year.

The major bases on Guam are Andersen Air Force Base, which often hosts US long-range bombers, and Naval Base Guam, which is home to a submarine squadron and is frequently visited by other warships.

It also hosts some 7,000 US military personnel, with more arriving as the Marine Corps relocates 5,000 Marines from Okinawa as part of a realignment plan. Their new home, Camp Blaz, is the Corps' first new base in 68 years.

Guam is an unincorporated US territory, meaning people born there are US citizens but have limited political rights while they live there.

The US presence there has often irritated the local population, as when thousands of US sailors were quarantined there after a COVID-19 outbreak aboard the aircraft carrier USS Theodore Roosevelt in spring 2020.

The US military presence also makes Guam a target.

North Korea has threatened it specifically in the past, and the island is believed to be a focal point of Chinese plans to neutralize US bases in the region in case of conflict.

China's DF-26, its first conventionally armed ballistic missile capable of reaching Guam, has been dubbed the "Guam Killer."