Louis LebÈgue Duportail, born in France, was educated at the military school of MÉziÈres, and considered an excellent engineer. When Congress instructed our commissioners in Paris to secure a few good engineers, Duportail was one of the four thus selected; and these were the only ones engaged by the express authority of Congress. On his arrival in this country, he was appointed colonel of engineers and promoted to the rank of brigadier-general on the 17th of November, 1777. He wintered with the army at Valley Forge, and after the battle of Monmouth, when the enemy left Philadelphia, he was sent to ascertain what defences would be necessary to its security, and to plan fortifications for the Delaware. He also superintended the strengthening of the defences at Fort Clinton and at Boston. In 1779, he was charged with confidential despatches to Count d’Estaing, but the subsequent repulse of the French and American troops at Savannah, and the departure of D’Estaing, rendered this mission fruitless.

In 1780, being sent to join General Lincoln at Charleston, Duportail was captured, together with this officer, during the summer; but through the efforts of Congress, they were both exchanged in the autumn. In 1781, he carried despatches to the Count de Grasse, and later the same year had charge of the engineering operations at the siege of Yorktown, being specially mentioned by Washington in his despatches after the capitulation. On the 16th of November, 1781, Congress conferred on him the rank of major-general, and granted him a six-months furlough to visit his native land. He resigned his commission in the United States army on the 10th of October, 1783, and in 1788 was named marÉchal-de-camp of the French army. In 1790, he was made minister of war, but resigned a year later, to accept a military appointment in Lorraine. Leaving the army in 1792, he returned to this country in 1794, and remained here until 1802, when, being recalled to France, he died at sea during the voyage home.