Though the U.S. and Denmark each had their own complex motivations in this exchange, “they turned upon the question of imperialism—declining in the case of Denmark and increasing on the part of the United States,” wrote the late historian Isaac Dookhan in a 1975 issue of Caribbean Studies. Ultimately, the U.S. would successfully pressure Denmark to sell the islands by threatening a military attack on the neutral nation during World War I.
Denmark had colonized the three islands—known as the Danish West Indies—back in the 17th and 18th centuries. It forced enslaved Africans to work on plantations producing products like sugar, which it profited from until the 1840s, when sugar prices fell.
Big changes also came in July 1848, when several hundred enslaved people on St. Croix revolted and won their freedom by threatening to burn the islands’ towns to the ground. After abolition, these newly freed people struggled to make a profit on exhausted lands and plantations that were small and old-fashioned compared with newer industrial operations, according to the Danish State Archives.
By the late 19th century, Denmark was finding it increasingly expensive to run the islands. Yet as early as the American Civil War, the U.S. was eyeing them as a possible economic and national security asset. This was because U.S. officials thought the islands could help secure American economic interests in the Caribbean. But they also worried a hostile foreign power might take control of them before the U.S. could.
“During the 1880s and 1890s, suspicion was directed mainly against Germany, which was developing interest in Latin America,” Dookhan wrote. “The fact that the German steamship company, the Hamburg-American Line, used St. Thomas as its regular refueling station tended to exacerbate those suspicions.”
The first negotiations between the U.S. and Denmark began in 1865, the year the Civil War ended. Secretary of State William Henry Seward actually negotiated a treaty with Denmark to cede the islands to the U.S. in 1867, but the Senate rejected it. This was probably partly due to an anti-expansionist sentiment that set in after the Civil War, and partly due to the fact that the Senate was angry at Seward over his support of President Andrew Johnson during his impeachment trial, notes the U.S. State Department.
Negotiations started up again in the 1890s but fizzled with the onset of the Spanish-American War in 1898. In the aftermath of that war, the U.S. gained the territory of Puerto Rico in the Caribbean and the territories of Guam and the Philippines in the Western Pacific (Puerto Rico and Guam are still U.S. territories; the Philippines won independence after World War II).
The U.S. was a larger imperial power now, with a greater interest in expanding. It had also set its sights on building the Panama Canal, and this made it even more interested in purchasing St. Thomas, St. John and St. Croix in order to secure the future canal’s route. Again, another secretary of state (this time John Hay) negotiated a treaty with Denmark. The Senate ratified the treaty in 1902, …[ ]