Blockades Don’t Always Work, or Do They?
The blockade tactic has been in the news recently. For the record, the British tried to blockade the U.S. twice. Once during the American Revolution and again during the War of 1812.
Were they successful? It depends on the lens through which one looks at the Royal Navy’s two attempts. Did either British blockade hamper U.S. traders doing business with other countries? Yes?
Did either blockade stop U.S. businessmen from conducting business overseas? No.
Did the attempt during the American Revolution and then again during the War of 1812 cause the U.S. economy to collapse or contract? No.
What prevented the Royal Navy’s blockade from being totally effective? After all, the Royal Navy had a successful history of blockading French and other European ports. The answer lies in distance, geography, number of ports, a lack of resources, and weather.
When British Prime Minister Lord North directed his admirals to blockade the rebellious 13 Colonies, distance and geography hampered the Royal Navy. From Kittery, Maine to Savannah, GA is roughly 875 nautical miles by sea. Along this coastline, there are at least 50 ports from which one could sail a large merchant ship of the era. France, on the other hand, has 10 – 15 along the Atlantic coast and three or four facing the Mediterranean.
Another issue is geography. By ship, the Royal Navy’s main base, Portsmouth, is in round numbers 3,000 Nautical miles (~3,400 statute miles) from New York City. Yes, it had bases in Bermuda, Halifax, and Fort Royal (Now Kingston, Jamaica), but other than Halifax, none had the infrastructure to support large fleet operations. Even Halifax was limited in space and winter weather.
By contrast, France was, in terms of sea miles, just around the corner. And there were no bottlenecks like the English Channel or the Skagerrak or, today, the Straits of Hormuz where the RN could easily prevent entry or exit.
In 1775, the Royal Navy had about 550 ships in commission. About a third were frigates and brigs that would or could be used for blockade duty.
Understand that to enforce a blockade, one must have ships off the entrance of the harbor so that the blockading force can capture any that try to enter or leave. Given that the search horizon from the mast top of an 18th-century frigate was, at best, 12 – 15 miles, doctrine suggested that a navy needed two, sometimes three ships on-station within sighting distance of the port entrance at all times to stop ships from using a port.
Radar, night vision goggles, electronic sensors, and other detection devices didn’t exist. And, unlike today where the U.S. and its allies replenish food, ammunition, fuel, etc. at sea routinely, this wasn’t done in the 18th and 19th centuries — replenishment required going to a port.
Transit times to and from station is another problem. From Portsmouth to Savannah could take six weeks or more and four weeks to return. Thus, to keep a ship on station for a month or two meant a navy needed one en route to, one returning, one on station in the blockade area, plus one in port refitting. That meant for every ship on station, you needed four in commission.
The math is ugly: 50 ports times four requires 200 ships. Even the RN didn’t have that many to spare from convoy duty, screening and scouting, for ships of the line, courier duty, etc. It didn’t have enough ships to enforce a blockade of the U.S. coastline.
At night, with no moon, it made it easier to slip in or out of a harbor. The last factor is weather, or more precisely, wind. The prevailing winds on the east coast of the U.S. are from the southwest, northwest, or just west, which means that to maintain station, ships are being blown away from the coast and have to work their way west, against the wind, to stay in their patrol area. North of Norfolk in the winter, besides wind, the ship and crew faces cold, snow and worse, freezing rain.
The point is that blockades can be an effective tool in peace and war, but they are resource sumps that few navies can sustain.
1840 Edmund Fry painting of HMS Pique.