Here’s what happened. Grenada became independent in 1974, and the first prime minister was Sir Eric Gairy, the head of a party called the Grenada United Labor party. In 1976, there was an election, which the United Labor Party won. There were allegations of election fraud, and another party, the New Joint Endeavor for Welfare, Education, and Liberation (“New JEWEL movement”), a Marxist/Communist party headed by a guy named Maurice Bishop made it their goal to get rid of United Labor.
There were a lot of confrontations. The police would regularly disrupt New JEWEL meetings and demonstrations and beat and arrest their leadership. There was a special police force called the “Special Reserve Police”, nicknamed “the Mongooses” who the government specifically used for disrupting demonstrations and harassing the opposition.
Things continue like this for the remainder of the '70s, with increasing demonstrations against Gairy and increased suppression by the government, and then in '79, Gairy goes overseas on a diplomatic trip, and there’s the rumor that the Mongooses were planning assassinate the JEWEL leadership while Gairy was gone.
In response to that, JEWEL decides its time to act. They attack the radio station and the barracks, and seize control of each, and arrest the government ministers. Bishop becomes the new PM. He then goes on to suspend the Constitution, outlaw all other political parties, and arrest his political opponents, including the Grenada Rastafarians. He also started taking aid from Cuba and the Soviet Union and started making plans to expand Grenada’s airport, which was, up to that point, a pretty pitiful thing, and he set up the People’s Revolutionary Army, headed by a guy named Hudson Austin, and supplied and trained by the Soviet Union and Cuba. Education programs and social spending were also increased, and Cuban aid helped with that too, and Cuban labor was used to start to build the airport.
Things went on for a while like that until 1983, when a split developed in the New JEWEL leadership. Bishop, the Prime Minister, wanted to try to improve relationships with the US, both because he was afraid that if the US got too angry it would intervene, and also because he wanted to counter the influence of the other faction, led by Deputy Prime Minister Bernard Courd, who had the backing of the People’s Revolutionary Army, and wanted to accept even more aid from Cuba and the Soviets and “speed up” Granada’s move to Communism.
On October 13, 1983, things between Bishop and Courd came to a head. Bishop ordered Courd to step down, and Courd responded by placing Bishop under house arrest and arresting his ministers. Over the course of the next week, there were street demonstrations by pro-Bishop forces, and on October 19th, Bishop’s foreign minister, who had escaped arrest because he had been in New York at the United Nations, came back and made a speech that inspired the crowd to free Bishop. Then the crowd, led by the Foreign Minister, went to Ford Rupport, a PRA base, to free the other government ministers imprisoned there. The army fired on the crowd, killing about 100 people, and rearresting Bishop and the ministers, including three influential supporters of Bishop. The Labour Minister was beaten to death by the Army, and then Bishop, three of his ministers, a union leader and the three Bishop supporters were lined up against a wall and shot.
General Austin then declared martial law, announced he was in control of the country, established a “Military Revolutionary Council”, set up a 24 hour curfew, warning that violators would be shot, and ordered the arrest of Bishop supporters. This went on for about four days, when the US government, along with forces from other Caribbean countries, claiming that the murder of Bishop and the general instability put the lives of ordinary Grenadans and American students at Grenada’s medical school at risk, invaded.
Was invading Grenada the right thing to do? I have no idea, but there’s the background.