When President Franklin Delano Roosevelt and Winston Churchill signed the Atlantic Charter in 1941, committing themselves to “respect the right of all peoples to choose the form of government under which they will live,” it looked as if the era of colonialism was finally coming to an end. In Puerto Rico, many felt that Luis Muñoz Marín, who would become the island’s first democratically elected governor in 1949, would come out strongly for independence.

In August 1943, 1,800 delegates and 15,000 supporters had gathered at the Sixto Escobar Stadium in San Juan, Puerto Rico, to launch the Pro-Independence Congress (CPI). Uniting leading figures in the Popular Democratic Party (PPD) with left-leaning nationalists and communists, it was a single-issue political movement whose ideals, as Muñoz Marín said in a message to the event, “without doubt are those of large numbers of Puerto Ricans.” A year later, Muñoz Marín and the PPD committed themselves to a plebiscite on the island’s status in these terms:

The PPD, opposed as it is to the permanence of the colonial government regime, solemnly undertakes to submit to the direct decision of the people of PR [Puerto Rico], no later than world peace is achieved — not through organizations or intermediaries in any form, but directly to each voter — in a vote entirely apart from elections, the consultation on the final political status that the people want for the full exercise of their rights and the best development of their future.