Most major American port cities (including those in Panama and the Philippines) were protected by coastal forts, many of which originally dated from the turn of the century and were thus on caretaker status as obsolete when the war began. In the continental United States, more than 30 new batteries designed to a common standard and with greater ranges were constructed before and during the war. These installations were chiefly shielded twin batteries of 6-inch guns as well as a few heavily casemated 16-inch batteries, the largest coastal defenses ever installed. A number of existing batteries were also casemated to protect against possible air attack. Older weapons from other batteries were often sent to other nations, such as Brazil and Canada, to bolster their coast defense. Fully manned in the opening months of the war, batteries were increasingly placed on caretaker status, and new construction (of more than 100 batteries) was halted by 1944.
Only the American-built harbor forts at Manila—most constructed early in the century—actually saw action, as Japanese forces advanced down the Bataan Peninsula between December 1941 and May 1942. U.S. mortar and gun batteries on Corregidor and other harbor islands and the twin turrets of Fort Drum in Manila Bay dueled with Japanese artillery, ships, and aircraft until the final American surrender in April and May. The forces at Drum prevented Japan's use of Manila Bay and also kept the Japanese from flanking the Bataan defenses by sea. Hawaii (Oahu), already extensively armed, was further fortified with naval turrets, including two removed from the sunken battleship Arizona, but none of its batteries saw action in the war.
In Canada, the key ports on the Atlantic (Halifax and Sydney, Nova Scotia) and the Pacific (Vancouver and Victoria) had been fortified earlier, usually with British 9.2-inch and smaller artillery in open emplacements. Several were upgraded with new guns and communications links. Although all of the Canadian forts were manned in support of convoy and military shipping, none saw action.
Major British harbors had been fortified at least since the mid-nineteenth century. Although some new emplacements were constructed, chiefly along the coast facing the mainland, British batteries were largely holdovers from the turn of the century and World War I. With Britain facing invasion in 1940, a host of emergency batteries were hastily built using cast-off 4-inch and 6-inch naval weapons. Pillboxes and other armored positions festooned coast and countryside. Sizable antiaircraft "sea forts" were built in the Thames and Mersey estuaries in 1942 and 1943 and were quite effective. Huge 14-inch and 15-inch guns emplaced near Dover controlled the Channel and could bombard Atlantic Wall defenses along the French coast. Unfortunately, British coastal batteries at Hong Kong (in 1941) and Singapore (in 1942) did little to slow the Japanese advances.
Coastal defense was extensively developed by the Axis powers, most specifically by the massive German Atlantic Wall. The Italian ports of Genoa and Venice were heavily defended with batteries, and the Germans added more after 1943. Few of these saw action, as Allied forces typically went around them or took them from behind. Japan rapidly fortified Pacific islands taken over in 1941 and 1942, and most of these facilities saw active combat, as did some of the extensive facilities protecting the Japanese home islands.
Christopher H. Sterling
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