That's one of the new revelations in an upcoming exhibit jointly organized by the Brooklyn Public Library and Green-Wood Cemetery. The Brooklyn Daily Eagle reports on it in "Brooklyn Examines Its Civil War History":
Although there were no battles fought in Brooklyn during the Civil War, as the third largest city in the Union at the time, Brooklyn provided “tens of thousands of soldiers to the Union Army” as well as a crucial industrial base, according to Richman, who is also the curator of “Enshrined Memories: Brooklyn and the Civil War.”
“I was amazed that a number who were killed in battle were brought back to Brooklyn to be buried when most casualties were buried on the field,” said Richman. He also noted that “Brooklyn was more sympathetic toward abolitionism than New York City,” pointing out that during the 1863 Draft Riots in Manhattan, many blacks fled to Weeksville, an established free black community in central Brooklyn.