Ticonderoga, a town of Essex co., New-York, enclosing the outlet of Lake George, 88 m. N. by E. of Albany; pop. in 1870, 2,590; in 1875, 3,401. It is at the junction of the Addison railroad, a branch of the Central Vermont, with the Champlain division of the Delaware and Hudson canal company's lines, and is the S. terminus of the Lake Champlain company's steamers. The portion of the town lying between Lakes George and Champlain is a lofty promontory, the terminus of a mountain ridge; Mt. Defiance at the extremity of the promontory is 750 ft. above the surface of Lake Champlain. The outlet of Lake George, 4 m. in length, has a fall in 2 m. of 220 ft.; and as the water never apparently varies in quantity, and is remarkably pure, it forms a very valuable water power. There is a vein of excellent graphite in the town, and about 25 tons of black lead are produced monthly by the "American Graphite Company," the only one in the United States. There are also extensive deposits of good iron ore, which is mined by the "Iron Company." Large quantities of lumber are manufactured, and there are an extensive sash and door factory, two founderies, two woollen mills, and a cotton factory of 20,000 spindles.

The town has 15 schools, a weekly newspaper, and Baptist, Congregational, Episcopal, Methodist, and Roman Catholic churches. Nearly the entire business portion was destroyed by fire, March 31, 1875; it is now being rebuilt with fine brick blocks. - The town is particularly remarkable for the prominent place its fortifications have held in American history. Early in 1755 the French, who had already occupied and fortified Crown Point, and caused a careful survey of Lake Champlain to be made, advanced to Ticonderoga and commenced a fortification there, which entirely commanded the passage of the lake. This fort they named Carillon (chime of bells), in allusion to the music of the waterfalls near it. It was afterward known as Fort Ticonderoga. Sir William Johnson was the commander of an English and colonial army the same year intended for the reduction of this fortress and Crown Point; but learning that the French had reenforced it largely, he contented himself, after defeating Dieskau at Lake George, with fortifying Fort William Henry at the S. end of that lake.

In 1757 Montcalm assembled a force of 9,000 men at Fort Carillon, and ascending Lake George attacked and reduced Fort William Henry, Aug. 3. In the summer of 1758 Gen. Abercrombie took the command of an expedition for the reduction of Fort Carillon, crossed Lake George with 15,000 men, and on July 8 attempted to take the fort by storm, but was repulsed with a loss of 2,000 men. In 1759 Gen. Amherst at the head of 12,000 men invested Ticonderoga, and the French, not having a sufficient force to hold it, dismantled and abandoned it, July 30; and soon after Crown Point was also abandoned. The English government then greatly enlarged and strengthened the two fortresses. The fort and field works of Ticonderoga extended over an area of several miles. After the cession of Canada in 1763, the fort was allowed to fall into partial decay, and was held by a small force. Upon the receipt of the news of the battle of Lexington, Col. Ethan Allen surprised the fort, May 10, 1775, and captured the garrison of 50 men and the artillery and munitions of war in the fort. (See Allen, Ethan.) The centennial of this event was celebrated in the town on May 10, 1875. In 1776, after an engagement between the British and Americans, the latter were compelled to take refuge under the guns of Fort Ticonderoga.- On June 30,1777, Burgoyne invested the fort, and on July 4 erected a battery on Sugarloaf hill (now Mt. Defiance), which completely commanded it and compelled the garrison to evacuate it the next night, sending their stores and munitions to Skenesborough (now Whitehall), and escaping themselves into Vermont. In September of the same year Gen. Lincoln made an attack upon the works, took Mts. Hope and Defiance, released 100 American prisoners, and took 293 of the enemy, an armed sloop, several gun boats, and more than 200 bateaux, but did not capture the fort.

After the surrender of Burgoyne the fort was dismantled, and the garrison retreated down Lake Champlain; some of them were captured by Capt. Ebenezer Allen. In 1780 Gen. Haldeman with a company of British soldiers advanced to Ticonderoga and occupied it for some time; and from this point Major Carleton made a diversion against Forts Anne and George, in favor of Sir John Johnson. After the war the fort fell into ruins; portions of the walls are still standing. - There is a history of Ticonderoga by the Rev. Joseph Cook (Keeseville, N. Y., 1858).