Quite a task

"Nearly a dozen sleds had crossed [the frozen Hudson River] without mishap, until suddently one of the largest cannons, an 18-pounder, broke through and sank not far from shore, leaving a hold in the ice fourteen feet in diameter. Undaunted, [General Henry] Knox at once set about retrieving the cannon from the bottom of the river, losing a full day in the effort, but at last succeeding."

This was a part of the monumental and heroic task of transporting the cannons that had been captured at Fort Ticonderoga to the Continental Army in Boston.