In August 1776, the American Revolution was on the verge of a disastrous end. General Washington found his troops outmanned and outmaneuvered at the Battle of Brooklyn, fought on land now part of Green-Wood. But thanks to a single heroic regiment, known as the “Immortal 400,” Washington was able to evacuate his men and they lived to fight another day.

Patrick O’Donnell, bestselling military historian, tells this story in his new book, Washington’s Immortals. In Green-Wood’s Historic Chapel O’Donnell will discuss the 1st Maryland Regiment, whose actions in many key battles changed the course of history. Using primary sources including letters, diaries, and pension applications, O’Donnell pieces together the stories of these brave men and, in the process, the larger story of the revolution.