in 1778, and promised compensation to owners whose slaves enlisted and survived to gain freedom. During the course of the war, about one-fifth of the Northern army was black. In 1781, Baron Closen, a German officer in the French Royal Deux-Ponts Regiment at the Battle of Yorktown, estimated the American army to be about one-quarter black. These men included both former slaves and free-born blacks. Thousands of free blacks in the Northern states fought in the state militias and Continental Army. In the South, both sides offered freedom to slaves who would perform military service. Roughly 20,000 slaves fought in the American Revolution. The birth of abolitionism in the new United States In the first two decades after the American Revolution, state legislatures and individuals took actions to free slaves. Northern states passed new constitutions that contained language about equal rights or specifically abolished slavery; some states, such as New York and New Jersey, where slavery was more widespread, passed laws by the end of the 18th century to abolish slavery incrementally. By 1804, all the Northern states had passed laws outlawing slavery, either immediately or over time. In New York, the last slaves were freed in 1827 (celebrated with a big July4 parade). Indentured servitude, which had been widespread in the colonies (half the population of Philadelphia had once been indentured servants), dropped dramatically, and disappeared by 1800. However, there were still forcibly indentured servants in New Jersey in 1860. No Southern state abolished slavery, but some individual owners, more than a handful, freed their slaves by personal decision, often providing for manumission in wills but sometimes filing deeds or court papers to free individuals. Numerous slaveholders who freed their slaves cited revolutionary ideals in their documents; others freed slaves as a promised reward for service. From 1790 to 1810, the proportion of blacks free in the United States increased from 8 to 13.5 percent, and in the Upper South from less than one to nearly ten percent as a result of these actions. Starting in 1777, the rebels outlawed the importation of slaves state by state. They all acted to end the international trade, but, after the war, it was reopened in South Carolina and Georgia. In 1807, the United States Congress acted on President Thomas Jefferson's advice and, without controversy, made importing slaves from abroad a federal crime, effective the first day that the United States Constitution