the hudson river chain refers to two chain booms and two chevaux de frise constructed from 1776 to 1778 during the american revolutionary war across the hudson river as defenses to prevent british naval vessels from sailing upriver. these defenses along the hudson river were overseen by the highlands department of the continental army. the most significant and successful was the great chain, constructed from west point in 1778, and used through 1782 after the war's end. the huge links for the chains were forged at iron works in orange county, new york. thumb|right|map of west point fortifications from 1775â1783 ==background== both the americans and british knew that passage on the hudson river was strategically important to the war effort. americans worked to devise plans to slow or block ship passage on the river, planning to attack enemy ships by cannons and mortar located at existing defensive forts or those to be constructed. it eventually constructed such obstacles across the river at northern manhattan, between forts washington and lee in 1776; at the newly constructed fort montgomery on the west bank on popolopen creek in 1776â1777 south of west point; a partially completed one at pollepel island in 1776â1777 north of west point; and the great chain (1778â1782) at west point. the largest and most important project was the latter chain at west point, which was reset each spring until the end of the war. attention was concentrated on the west point area because the river narrowed there, and curved so sharply that, together with winds, tides and current, ships already had to slow to navigate the passage. creating more obstructions on the river enabled the shore batteries to work their cannons against the enemy. ==fort lee to fort washington chevaux-de-frise (1776)== thumb|right|400px|1777 map detail showing the chevaux-de-frise between fort lee and fort washington as part of the barriers erected across the river, the army constructed chevaux-de-frise, an array of logs sunk underwater, between fort washington on the island of manhattan, and fort lee across the river in new jersey. the logs were intended to pierce and sink any british ships that passed over it. an opening was left for the passage of american ships. after the british learned of the opening from a local resident, they successfully passed through the barrier several times.diamant, chaining the hudson, 1989 the british [[battle of fort washington|capture
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