French submarines at Casablanca

Redoutable-class sub from A&A War at Sea

Today we think of submarines as primarily used for the disruption of trade and useful for clandestine missions. Modern nuclear submarines are large and can remain at sea for months on end. Even in World War II large "fleet" submarines ranged over vast distance sin support of fleet operations and  ravaging enemy trade across the ocean.

But the very first submarines, limited in size and endurance, were primarily coast and harbor defense vessels. They were designed to prevent the close blockade of harbors by an enemy fleet. While most of the major navies such a s Japan, the United States, Britain and Germany concentrated their efforts on larger, ocean-going subs, the French Navy still had  a very substantial number of these smaller subs on hand Casablanca was a major naval base for them.  At Casablanca in 1942 there were eight of them, comprising the 16th and 18th submarine squadrons. All were of the so-called 630-ton class, which give some idea of their diminutive nature. They actually displaced a little more, some 800 tons, but were nonetheless very small with a crew of under 50 men. The clearest manifestation of their defensive role was the arrangement of their torpedo tubes. Five 550 millimeter torpedoes and two 400 millimeter torpedoes were carried in external tubes that could not be reloaded at sea.  There was just one internal torpedo tube which carried just a single reload weapon.

The external weapons undoubtedly helped keep the cost, complexity and size of the boats down from what internal tubes would have, but just as obviously meant the boats were not useful for long-range cruises or raids.

In addition to the eight coastal boats, the French and their 4th Submarine Squadron present at Casablanca, with three larger Redoutable-class subs. These were true ocean-going subs more than twice the displacement of the coastal boats and carrying four forward-firing torpedo tubes with 550 mm torpedoes. Like the smaller boats these also increased their firepower with externally mounted tubes carrying a  total of three 400 mm torpedoes and five 550 mm weapons. As in the smaller boats the larger external tubes could not be reloaded at sea, although the 400 mm tubes could.

Altogether the French submarine force at Casablanca was substantial and well-suited to defend the harbor and coast.