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The Great Bridge - Ticonderoga, NY to Mount Independence, VT


Reconstructed drawing of the Great Bridge caissons.

In 1983 the Champlain Maritime Society (CMS), a predecessor of the Lake Champlain Maritime Museum, undertook an ambitious project on the bottom of Lake Champlain between Fort Ticonderoga and Mount Independence. The goal if this group formed to study and document the submerged cultural remains in Lake Champlain was to survey the bottom of the lake and locate the remains of the “Great Bridge” that spanned this section of the lake in 1776 connecting these two formidable American fortifications.

Prior to getting in the water, the CMS conducted extensive research in regional institutions, scouring all available sources to learn everything possible about the history and construction of the “Great Bridge.” Based upon the results of the research, they formulated a strategy that would lead the efforts of the research team in their underwater operations. When the plan to use side scan sonar fell through, the CMS research team decided to use a dive team to conduct a visual survey of the bottom using a compass-guided grid system in a tightly-defined area. The project began in mid August on the Ticonderoga side of the lake at “the old landing” where the bridge had its western terminus.


Contemporary painting of the Great Bridge, by Henry Rudyear.
Courtesy of Fort Ticonderoga.

The research conducted prior to the beginning of the survey suggested that the area around the bridge’s western terminus at Ticonderoga was also the site of an active shipyard and harbor during the Fort’s years as an important military post. In addition, during most of the nineteenth century, the site served as an operational steamboat landing with an extensive dock system. To complicate matters further, the water in this part of Lake Champlain is very murky, severely limiting visibility underwater and the bottom of the lake in the small bay where the survey was to take place was extremely soft and choked with dense aquatic weed growth.

The dive team quickly located the remains of the nineteenth century steamboat dock built of rock-filled wooden cribs and noted that it was consistent with other similar structures around Lake Champlain. Then, in rapid succession, one, then another, and yet another “Great Bridge” caisson was located. These structures were built in log cabin-style with wooden spikes or “treenails” pinning the logs together at their mortised corners. The center of each twenty-four-foot square structure had a series of plank floors supporting the stone ballast used to hold the caisson on the bottom. Then, to everyone’s great surprise the lower remnants of a ship’s hull appeared. Almost immediately thereafter another hull was found protruding from the soft, silty bottom of Lake Champlain. Thus ended the very first day of the survey!