Green-Wood Civil War Project

A brochure near this field explains why these graves are here (June, 2007):
WHY ARE THESE GRAVESTONES HERE?
During the last five years, The Green-Wood Historic Fund's Civil War Project has identified close to 3,000 Civil War veterans buried at the cemetery. Of those, approximately 1,200 are in unmarked graves or have unreadable gravestones. Led by our historian, Jeff Richman, volunteers have filed requests with the Veteran Administration for gravestones, which have arrived in the last few months. The Cemetery grounds crew has set them out on display and in the ensuing months, they will be placed upright at the gravesite of each veteran.

Links: National Public Radio (interview with Jeff Richman). New York Times video
Address: 500 - 25th Street Brooklyn, New York 11232-1317 (718) 768-7300 Official Web Site

I also have pictures of an interesting Civil War Memorial at Calvary Cemetery in Queens