The American Revolution began in April, 1775 in Boston and quickly settled into a stalemate with the British holding Bunker Hill, a peninsula in the inner bay, loyalists citizens bottled up in Boston, also a peninsula, and the continental army under General Washington commanding a ten-mile long cordon of rebel troops surrounding the entire bay including a third peninsula. This peninsula, Dorchester Heights, was a 112-foot high hill looking down on the British within easy artillery range less than two miles away across the bay. The military potential of the Heights was known to Washington and British General Howe, but was unoccupied because the Americans had no artillery to place there and the British, knowing this, had no interest in paying the huge price required to capture it.
May 10, three weeks Lexington and Concord, colonial militia under the joint command of Benedict Arnold and Ethan Allen captured Fort Ticonderoga with its considerable artillery.
Two months later General Washington assumed command of colonial troops in Boston, where the war began. Militia colonel Henry Knox reported for duty to Washington October 24 and volunteered to retrieve the artillery at Fort Ticonderoga. Though he was only a 25 year old bookseller whose entire knowledge of military matters and artillery was gained from books in the back of his Boston store, Washington gave him the assignment!
Washington hadn’t tried to retrieve captured cannon from the Fort because the 150-mile trip straight across the Green Mountains was impossible then—and still is today. A former student of mine, now a General Manager in J.B. Hunt Truck Lines, calculated the best route now at 223 miles over mostly interstate highways I-87 and I-90. If handled today by Hunt, it would require a small fleet of 53-foot flatbed semi-trailers each costing $800 each. Once loaded, they would have the load in downtown Boston in under 6 hours!
The trip occurred in winter in an area much colder and wetter than here. Even now, snow closes the fort on October 20. But, snow was their friend, not their enemy, because after the first sleds crossed over it and compacted it into ice, the trailing sledges would be gliding on ice.
Knox set out from Boston to NYC in late November and from there north to Ft. Ticonderoga, arriving December 5. En route he had procured 80 oxen teams and 42 sledges [sleds] each weighing 5400 pounds. Onto these were loaded 58 disassembled 12-inch mortars and 18-pound cannons weighing respectively from 1500 and 5,000 pounds each.
Beginning in the Adirondack Mountains with the Green Mountains to their east at an elevation of approximately 3,000 feet, they would descend 1000 feet getting to Albany, another 1000 feet from there to Springfield and a final 1000 feet from there to Boston at sea level. Some places were as “steep as a roof.” The terrain was described as “rough forest roads, freezing lakes, and mountain wilderness.”
Page 2 of 2 - Departing on Dec 9 they spent 8 days floating on barges 35 miles south on Lake George to its southern tip where they began their arduous trip overland on sled. The route roughly paralleled the Hudson River to Albany, necessitating crossing it four times on barges.
Fortunately, it snowed on Christmas day.
Departing Albany they turned east and crossed the Berkshire Hills, switching at Springfield to horses to increase their speed, and arriving in Boston January 24 without the loss of a single cannon.
By my calculation, they averaged about 8 blocks an hour or 20 yards in a minute or seven paces or 60 feet a minute. In a bit over five weeks they had accomplished the impossible: they had moved 119,000 pounds of artillery 300 miles through impenetrable terrain. General Washington immediately gave Knox charge of all artillery.
After two nights of artillery fire to hide the noise of their advance preparations, the continental army moved the mortars and cannon up Dorchester Hill the night of March 4. The next morning British troops looked up at a menacing row of cannon and mortar well within range of their fortifications. The British field pieces could not be elevated enough to reach the Heights. The jig was up for them, and within days British troops with 4,000 loyalists departed for Halifax, Nova Scotia. General Howe had been outsmarted by a “rabble in arms.” [*]
West Point cadets, including Dwight Eisenhower, study this extraordinary feat to learn the importance in war of terrain, logistics, and transportation. The Act creating the interstate system signed June 29, 1956 by President Eisenhower from his hospital bed at Walter Reed Medical Center was “National System of Interstate and Defense Highways.” 
McCullough, David, “1776”, NY : Simon and Schuster, 2005, 1-98.
Earl Swift, “Big Roads,” Boston: Houghton Mifflin Harcourt, 2011, 186-7.