As you can see from columns on the right side, all of these executions took place in New York in 1741. That puts them as part of the New York Conspiracy.

1741 in the city of New York was a tense time in race relations. Several years prior, a suspected slave rebellion in New Jersey had been foiled in 1734. In 1736, a major slave uprising occurred on the British colony of Saint John, in the Carribbean.

The British empire had declared war on the Spanish empire back in 1738, and the war was ongoing. In 1739, the Stono Rebellion in South Carolina took about 20 white lives before it was suppressed. At the time, there was widespread suspicion that the rebellion was provoked by Spanish agents, and the goal of the South Carolina slaves was to escape to Spanish Florida.

Memory of these past slave rebellions raised concerns in New York city, because it had the second largest slave population in the 13 colonies, after Charleston.

What we know happened was there was a rash of fires in New York city in March and April of 1741. When an Irish indentured servant was brought in on charges of theft, she claimed to know about a plot between slaves and indentured servants to start the fires and overthrow the social order of the city. Very quickly, the people she named were brought in, and they implicated others, some 200 in all.

In addition to the thirty or so individuals who were hanged, burned or gibbeted, approximately 80 more were to be transported to the Carribbean, facing grueling conditions when they got there. Seven white men were pardoned, but were forbidden from setting foot in New York again.

If you want to read more about the events of the alleged conspiracy, you might read New York Burning: Liberty, Slavery and Conspiracy in Eighteenth Century New York by Jill Lepore. It is an engaging pop-history treatment of the subject.