On July 31, 1777, Marquis de Lafayette, 19, was made a major-general in the Continental Army. From the article:
"Marquis de Lafayette becomes a major-general without pay
On July 31, 1777, a 19-year-old French aristocrat, Marie-Joseph Paul Roch Yves Gilbert du Motier, Marquis de Lafayette, accepts a commission as a major-general in the Continental Army—without pay.
During his service as the Continental Congress’ secret envoy to France, Silas Deane had, on December 7, 1776, struck an agreement with French military expert, Baron Johann DeKalb, and his protege, the Marquis de Lafayette, to offer their military knowledge and experience to the American cause. However, Deane was replaced with Benjamin Franklin and Arthur Lee, who were unenthused by the proposal. Meanwhile, King Louis XVI feared angering Britain and prohibited Lafayette’s departure. The British ambassador to the French court at Versailles demanded the seizure of Lafayette’s ship, which resulted in Lafayette’s arrest. Lafayette, though, managed to escape, set sail and elude two British ships dispatched to recapture him.
Following his safe arrival in South Carolina, Lafayette traveled to Philadelphia, expecting to be made General George Washington’s second-in-command. Although Lafayette’s youth made Congress reluctant to promote him over more experienced colonial officers, the young Frenchman’s willingness to volunteer his services without pay won their respect and Lafayette was commissioned as a major-general.
Lafayette served at Brandywine in 1777, as well as Barren Hill, Monmouth and Rhode Island in 1778. Following the formal treaty of alliance with Lafayette’s native France in February 1778 and Britain’s subsequent declaration of war, Lafayette asked to return to Paris and consult the king as to his future service. Washington was willing to spare Lafayette, who departed in January 1779. By March, Franklin reported from Paris that Lafayette had become an excellent advocate for the American cause at the French court. Following his six-month respite in France, Lafayette returned to aid the American war effort in Virginia, where he participated in the successful siege of Yorktown in 1781, before returning to France and the further service of his own country."