VI. The World Wars and the Interwar Period, 1914–1945 > K. World War II, 1939–1945 > 8. Naval Warfare and Blockade, 1939–1944
  The Encyclopedia of World History.  2001.
8. Naval Warfare and Blockade, 1939–1944
The gross tonnage of the merchant fleets of the leading nations in 1939 reflected the overwhelming advantage that Great Britain and its subsequent allies enjoyed on the sea. The ships of Norway, the Netherlands, and Belgium, most of which escaped when these countries were overrun by the Germans in 1940, took service with the British and helped to build up the pool of United Nations shipping.
Merchant tonnage, 1939
Great Britain21,001,925 Japan5,629,845
United States11,470,177 Germany4,482,662
Norway4,833,813 Italy3,424,804
Total43,617,844 13,537,311
In 1939 the world tonnage for merchant ships of 100 tons or over was 68,509,432. More than half of this was destroyed, largely by submarine or air attack, in the course of the next five years. Yet, so energetic was the shipbuilding program, carried out largely in American yards immune to air attack, that by May 1945, Britain and the U.S., through the war shipping administration, disposed of over 4,000 ships with a deadweight tonnage of 43 million. The Germans, Italians, and Japanese, on the other hand, found it increasingly difficult to make good their losses, and by 1945 their fleets, merchant and naval, had been almost completely eliminated.
1939, Sept. 3
The British government proclaimed a naval blockade of Germany.  2
Nov. 21
The British tightened the blockade on German imports and announced that German exports likewise would be halted.  3
Dec. 1
From this date neutral shippers were advised to obtain a “navicert” or certificate from British consular officials. These navicerts enabled a cargo to be passed through the patrols established by the British government in concert with its allies. Italy, the Netherlands, Belgium, and Japan protested against the British blockade measures.  4
Dec. 8
The U.S. Department of State questioned the British practice of seizing German goods on neutral vessels, and challenged (Dec. 14) the diversion of U.S. ships to British and French control bases. The State Department also protested (Dec. 27) against the British examination of neutral mail in the search for contraband.  5
Dec. 17
The German battleship Graf Spee was blown up by order of the commander.  6
The Encyclopedia of World History, Sixth edition. Peter N. Stearns, general editor. Copyright © 2001 by Houghton Mifflin Company. Maps by Mary Reilly, copyright 2001 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.