The Blockade, the Submarine and America's Entry into the War


1.  In World War I, the United States was predisposed to sympathize with the Allied cause.
2.  America's major ties of culture and language were with Britain
3.  Americans entertained a sentimental tie with France due to the aid which it supplied during the American Revolution
4.  Economic ties to the Allies (trade and loans)
5.  American reaction to the rape of neutral Belgium
6.  Annoyance at German sabotage in U. S.
7.  Allied propaganda (America's view of the war came chiefly through Britain) However, predisposition to sympathize did not mean a readiness to fight for the Allies.  As important as the above factors were, they would probably not have been enough to push the profoundly isolationist U. S. off the neutral fence without the addition of another, highly emotional issue - German submarine warfare.
It was unlimited submarine warfare as practiced by the Germans first in 1915 and then all-out in 1917 which finally brought the United States into World War I.
To understand the question of German submarine warfare, one must examine the whole question of blockade, counter-blockade, and neutral rights in the First World War.
Blockade:  form of economic warfare in which one power attempts to cut off its enemy from acquiring the imported resources necessary to maintain the war effort.  Ordinarily practiced by the power which controls the trade routes.  (In modern times, this usually means the sea lanes)
In the last few centuries, England has been the power most often associated with the weapon of blockade.
Changes in the nature of war which have made blockade an increasingly important weapon:
1.  Growing complexity of war which has meant that virtually no nation is absolutely self-sufficient in the materials and products necessary to conducting a war.
2.  Changes in naval architecture which have increasingly differentiated military and commercial vessels, making it impossible to convert commercial vessels into military vessels in time of war.  This has rendered merchant ships increasingly unable to defend themselves.
In 1914, the Allied Powers enjoyed a clear naval superiority over the Central Powers.  To begin with, England possessed by far the largest navy in the world.  France, Japan, and Russia also had substantial navies of their own; and, in 1915, they were joined by another naval power - Italy.  Only two of the Central Powers possessed navies - Germany, with the world's second most powerful, and Austria-Hungary with its relatively small fleet concentrated in the easily blockaded Adriatic Sea.
In short, the Central Powers were even more outnumbered at sea than on land.
By March, 1915, the seas were swept clear of German warships; and for the rest of the war, the surface belonged to the Allies. From the beginning of the war, the Allies began using the weapon of blockade against surface ships bringing supplies to the Central Powers.  The goal was to starve out Germany and her allies.
When a nation's ships are swept from the seas, as Germany's were in World War I, it is perfectly legitimate and natural that that nation will try to fill the gap by reliance on neutral shipping.  It is equally true that a blockading power, like Great Britain in World War I, will try to interdict neutral shipping to the extent possible while still observing the widely-recognized rights of neutrals in time of war.
Generally speaking, in a wartime situation, neutrals try to carry on their commerce as they did in peacetime, while the blockading power or powers try to find every way they can to limit neutral commerce with their enemy.  This usually leads to friction between neutrals and blockaders.
Legitimate prize:  any enemy ship seized in time of war.  Such a seizure, which in peacetime would constitute piracy, is perfectly acceptable in a wartime situation.
Paper blockade:  any blockade which is simply declared by one country against another, but is not made effective by stationing enough naval forces around the enemy to cut off its trade with the outside.  According to international law, paper blockades are illegal. 
Coming into the First World War, the recognized means of establishing an effective, and therefore a legal blockade was to station warships off an enemy port.
Contraband:  material destined for the enemy which had a military potential.
In 1914, international law generally recognized two forms of contraband:
1.  Absolute contraband:  goods exclusively used for war headed for the enemy (weapons, shells, military uniforms, etc.)
2.  Conditional contraband:  goods which may have either a military or a peaceful use, which are destined for the armed forces or a government department of an enemy power (oil, steel, motors, etc.)
According to international law, these two forms of contraband had to be treated on a somewhat different basis by the blockading power.
Rules for dealing with neutrals (circa 1914):
1.  Ships and citizens of a neutral country had certain widely recognized rights.
2.  Neutral ships were never legitimate prize; all that a blockading power had a right to do was to seize contraband within their cargos.
3.  Neutral goods (ie. those owned by citizens of a neutral country), whether on a neutral ship or an enemy ship, were safe unless they were contraband and headed into a legitimately blockaded port.
4.  Even enemy goods, if carried on a neutral ship, were safe from confiscation unless they were contraband and headed for a blockaded port.
5.  Blockading powers were to take great care to avoid actions that might place neutral lives in danger.
In World War I, the Allies were attempting to establish a complete and effective blockade of Germany despite the protections afforded neutrals and neutral commerce. To accomplish this required:
1.  Cutting off direct neutral trade with Germany even in non-contraband goods
2.  Cutting off German importation of good - both contraband and non-contraband - through her neutral neighbors (Holland, Denmark, Sweden, and Norway)
3.  Avoiding the antagonizing of neutrals (esp. the United States) to the point where they would retaliate
General von Moltke the Younger had removed Holland from the original Schlieffen Plan on the grounds that if the plan did not work, and the war became protracted, Germany would need a neutral "window" through which to trade with the outside world.
Ironically, the actions of the United States during the Civil War, which had been aimed at cutting off European trade with the Confederacy, provided the British with the needed precedent for closing Germany's neutral windows.
Most goods had been brought into the Confederacy in a two-step process: 
1. Large European merchant ships brought them to neutral Caribbean islands (esp. Cuba) where they were off-loaded. 
2. The goods were then reloaded onto small, fast blockade runners to be run past the Union blockade.
Stopping these blockade runners was extremely difficult.  By contrast, the Union navy found it much easier to stop the European cargo ships sailing into the Caribbean.  To do so, however, meant interfering with neutral ships on the way to a neutral port - a violation of international law as understood in the mid-19th century.  To solve the problem, the United States unilaterally 'rewrote' international law by creating the Doctrine of Continuous Voyage.
Doctrine of Continuous Voyage:  it is legitimate to intercept a neutral cargo bound to a neutral port IF that cargo is clearly not intended for the use of the neutral inhabitants, but is instead on the first leg of a voyage to an enemy country, the second leg of which will be a short sea voyage from the neutral port to an enemy port. Using this new doctrine, the union intercepted European ships bringing goods into the Caribbean and removed absolute contraband (the doctrine did not apply to conditional contraband) even though those ships were headed for what were technically neutral ports.
Although some of the nations involved complained loudly about the practice, calling it piracy, Britain was relatively muted in its complaints and refrained from condemning the practice as absolutely illegal.  In doing so, the British were acting in a far-sighted manner, realizing that they might someday have use for the new principal.
In World War I, the Allies used the doctrine of continuous voyage to cut off Germany's trade through neutrals.  The doctrine, as worded by the United States in the Civil War, was adequate to cut off trade through Norway and Sweden, (to wit, stopping goods that would reach Germany by a second, shorter sea route.)  In addition, the Allies "revised" the definition to include goods which would reach the enemy by means of a short overland journey, thus closing off Holland and Denmark.  The Allied blockade continued to tighten as the years went by until it eventually closed off all neutral trade with the Central Powers.
Questionable procedures in conducting the British blockade:
1.  Continually expanding the list of goods considered to be contraband
2.  Moving goods from the list of conditional contraband to the more restricted list of absolute contraband
3.  Issuing import licenses to neutral countries, which allowed them to import goods for home use, but which forced them to guarantee that they would not sell any of those goods to the enemy
4.  Setting import quotas on neutrals (such as Holland and Denmark) based on their pre-war import figures, thus assuring a supply for their home markets, while making certain that they would have no surplus to sell to the enemy
5.  Forcing neutral ships to enter British ports for leisurely search and, once in port, searching and censoring their mail bags
6.  Blacklisting of neutral firms conducting trade with the enemy
7.  Refusing to fuel neutral ships carrying the goods of a blacklisted firm
The case of food provides an interesting example of Britain’s pressing the envelop of international law.  In the past, food had usually not been considered contraband of any form; however, since it was military policy to starve the German population - civilian as well as military - into submission, the British placed food on the list of conditional contraband as soon as the war began.  Then, when Germany declared rationing in January, 1915, food was moved to the absolute contraband list, to cut off importation through neutral countries.
How the Allies enforced the blockade:
1.  Traditional means:  surface ships on station in the North Sea and Mediterranean
2.  Untraditional means made possible by new technologies
a.  Mine fields
b.  Submarines
War Zone:  a whole area declared to be dangerous to neutral shipping.  This violated the long established view that an effective blockade was one enforced with surface ships stationed off enemy ports.
The British declared the whole North Sea a "military area" or war zone as early as November 1914.
To be safe, neutrals were required to channel their commerce over British-controlled 'lanes' through the North Sea, thus making it easier for the British to stop and search them.
Allied justification for these questionable measures:
1.  The cloudy state of international law
2.  Necessities of war
3.  Uncivilized conduct of their enemies
4.  Precedents set by the United States in the Civil War
Not surprisingly, the Central Powers argued that much of what the British were doing was illegal.  So did most of the neutrals, including the U. S. However, the U. S. limited itself to complaining; it did not use the one real weapon it had - an embargo.
Embargo: the cessation of trade with a belligerent power put into effect by a neutral power. (Major example:  the embargo used by the Jefferson Administration against both Britain and France during the Napoleonic Wars.)
The Allies particularly feared an embargo by the United States since they purchased a good deal war material from American firms.
Why the U. S. did not use an embargo:
1.  Economic ties with the Allies
a.  Most trade was with the Allies (in 1914, this wartime trade had helped prevent a recession in the U. S.)
b.  Most American loans went to the Allies, giving the U. S. a financial stake in their survival
2.  Political considerations:  no minority president such as Wilson could safely institute an embargo which might plunge the U. S. into a depression
3.  General public sympathy with the Allied cause
4.  While the Allies were disrupting trade, the enemy's counter-measures were taking American lives
German use of submarines and the loss of American lives became the key cause of American entry into the First World War.
The military use of submarines was pioneered by powers under blockade by surface ships:
1.  American colonies in the revolution (American submarine Turtle unsuccessfully attacked Br. frigate, Eagle)
2.  Confederate States of America (during the Union blockade of Charleston, South Carolina, the Confederate submarine Hunley sank the Union frigate Housatonic)
Late nineteenth century improvements in submarine technology:
1.  Engines replaced handpower
2.  Use of two engines:  petrol for surface; electric under water
3.  Improved sea-worthiness
4.  Self-propelled torpedoes
5.  Use of radios with increased range
6.  Improved periscopes
Ironically, Germany lagged behind other leading powers including England in the development of submarine warfare.  In this respect, Admiral Tirpitz was very traditional.
Germany did not commission its first submarine - the U-1 (short for Unterseeboot-1) - until 1906; and even though Germany began to catch up in the opening years of the 20th century, it was still not prepared to unleash a major submarine campaign when World War I began.
Unterseeboot:  (literally "undersea boat") the German word for submarine.
In World War I, the Germans found that submarines did not hunt well in groups and so sent the boats out individually.  (The reverse of World War II where submarines hunted in “wolf packs”.
At first, the Germans used U-boats primarily against military targets.
First sinking:  U-21 sank the British light cruiser Pathfinder.
Best single day in the war for a U-boat:  Sept. 21, 1914 when U-9 sank three British armored cruisers.
The German use of submarines against merchant and passenger ships, usually without warning, increased as the Allies tightened their blockade, a blockade that often utilized means which the Germans regarded as illegal.
From the beginning, there were two schools of thought in Germany regarding the use of submarines:  (1) those who wanted to proceed carefully and avoid upsetting neutrals, esp. the United States; (2) those who wanted to make maximum use of submarines to starve Britain before the British blockade starved Germany. During the war, these two schools alternated in winning the support of the kaiser.
Rules of warfare against civilian shipping:
1.  Give warning and an opportunity to surrender
2.  To send a boarding party onto the ship to determine its status (enemy or neutral) and examine its cargo for contraband
3.  To take take a prize (i. e. an enemy ship which had been captured) into port if at all possible
3.  To be certain of the crew's safety if it was deemed necessary to sink the prize
4.  To allow a neutral to proceed on its journey after removing contraband
For a submarine to operate within these existing laws was impractical if not impossible.
1.  To give warning or send out a boarding party meant to surface where the submarine was vulnerable to ramming or shelling.
2.  A submarine was usually in no position to take a prize into port and was too small to take aboard the crew.
3.  It was usually too dangerous to try to tow the ship's boats close to shore. The Allies increasingly equipped their merchant and passenger ships with guns that could be used against a surfaced submarine.  They also sent out Q-Boats.
Q-Boats:  Especially constructed gunships disguised as merchant vessels.
Nevertheless, many German U-boat captains did their best to live up to international law, esp. early in the war.  Others, however, ignored all such laws as soon as they were given the green light by the German admiralty.
German War Zone:  In February, 1915, in answer to the British declaring the North Sea a "military area", the Germans declared all waters surrounding Great Britain and Ireland to be a war zone in which neutral as well as the enemy's commercial shipping would be in danger from submarine action.
Militarily the measure was highly effective as the monthly tonnage sunk sky-rocketed.  However, it was a diplomatic disaster as neutrals, esp. the United States, became infuriated with the German policy which was far more dangerous to neutral lives than the British irregularities.
The Germans, if they wished to strike back at the British blockade that was strangling them, had no alternative but to use submarines aggressively.  For its part, the United States adhered strictly to existing international law and refused to recognize the Germany's dilemma.
Lusitania:  British passenger liner sunk off the coast of Ireland in May, 1915, with the loss of many lives including 128 Americans.  It became an international symbol for the devastation caused by unrestricted submarine warfare.  Immediately afterwards, the Wilson Administration threatened to break off diplomatic relations with Germany (and perhaps worse) if the Germans did not reign in their submarines.
On this occasion, the Germans backed down, agreeing to limit the use of their submarines against commercial shipping, especially against passenger ships which were likely to have neutrals among their passengers.
Reasons the Germans backed off in 1915:
1.  Failure of submarines to fulfill promises of supporters to bring Britain to its knees in 6 weeks
2.  Hardening stand of the U. S.
3.  Realization of German decision-makers that Germany did not yet possess enough submarines to win the war
Reasons for resumption of unrestricted submarine warfare in 1917:
1.  Complete support from the High Command (Hindenburg and Ludendorff) who rejected the idea of a compromise peace and realized that Germany's only real hope for victory was to cripple Britain
2.  Support from the German Admiralty under Admiral von Scheer, who reported to the kaiser after the battle of Jutland that Germany's surface fleet had no realistic hope of breaking the blockade
3.  Belief that the United States would not get involved in a European war; and that even if she did, she could not bring her military potential to bear fast enough to make a difference
4.  Construction of adequate numbers of submarines to be decisive (or so the Germans thought)
Battle of Jutland (May, 1916):  only major naval battle of the war fought in the North Sea.  Von Scheer had hoped to lure the British Grand Fleet commanded by Sir John Jellicoe into a trap and destroy it in pieces.  In fact; the trap was almost sprung on the Germans.  Although in the end, the German fleet enjoyed a tactical advantage, having sunk nearly twice as much British tonnage, the British won in a strategic sense.  The High Seas Fleet was unable to break the blockade and was forced to retreat into home waters.  This finally convinced the admiralty that the German navy could never play a major role in deciding the war's outcome.
Resumption of Unrestricted Submarine Warfare came in February 1917.  To add insult to injury, the Germans only informed the U. S. on Jan. 31, one day before it went into effect.
Zimmermann Telegram:  incredible diplomatic blunder in which the new German Minister of Foreign Affairs, Arthur Zimmermann, sent a coded telegram to the Mexican government a joint war effort against the United States.  Insult was again added to injury when the message was sent in the American diplomatic pouch.  (President Wilson had afforded the Germans that courtesy to make possible easier diplomatic contact with their embassies overseas.)  The British intercepted and then leaked the message (probably using "black ops" of their own.)  Not only did the Germans not deny it, they publicly acknowledged the attempt in the Reichstag.
As a result of these provocations, the U. S. declared war on Germany in April, 1917.
The German gamble on submarine warfare, after coming very close to success, failed when the Allies went back to an old concept of warfare at sea - the use of the convoy system.
Convoy System:  ships would sail in groups protected by warships.  In the early modern period, it had been the basis of the Spanish "fleet system" that for centuries connected Spain with her American colonies.
Arguments against:
1.  Would require too many warships needed by the Grand Fleet
2.  Would provide too large a target to U-boats
3.  Convoy would be too slow, travelling only at the speed of the slowest ship
4.  Arrival in Britain would choke port facilities
Arguments for:
1.  Strength in numbers
2.  Easier to protect ships sailing together by using a screen of destroyers
3.  Convoy steaming directly ahead at full speed would be just as fast as lone merchant ships zigzagging across the ocean
4.  Since it already had its instructions, the convoy could maintain radio silence 5.  Psychological advantage: in a convoy, they could be picked up if their ship was sunk
6.  Given the number of ships involved, convoys would not overcrowd British port facilities
When the convoy system was put in place, the prime minister, David Lloyd George, who supported it, purged the British admiralty of its opponents, including Jellicoe, who was replaced as commander of the Grand Fleet by Admiral Beatty.
After convoys were established, the monthly tonnage sunk by submarines fell off drastically.  Because of the system, no troop ships coming from America, were ever sunk.
Destroyer:  small warship which now proved especially useful for convoy duty.  They became the basis of defense against submarines
By taking 223 neutral American lives and sinking a few American ships, Germany had brought into the war the nation which would eventually tip the scales against her.