If there was any doubt about the impact of submarines in an open ocean war, they were dispelled for even the harshest critic in 1914-1915. The surprise attacks form the German U-boats were stunning to the public at large as they watched ship after ship damaged and sunk. While some in the American naval leadership tried to push away the critics, the inclusion of open ocean shipping helped to settle the nature of the threat.

At the beginning of the war, many ships were vulnerable since they traveled alone. Not only that, but shipping schedules had been routinely published in the press. It would not take much detective work to gather that information and direct it to the U-boats that were beginning to figure out how to sink their prizes. Their efficiency gained strength all through the war until the British broke down and started shipping in escorted convoys. The old system of convoys was abandoned during the beginning of the age of steam since it was felt that independent seam powered ships could maneuver their way out of danger. It was also felt that the use of warships in convoys was a precious waste of resources.

The use of merchant convoys did not begin until 1917. When they began in earnest, the threat of the German submarines was effectively diminished.

But in 1915, lessons were being learned on both sides.

The single biggest lesson was with the sinking of the Lusitania.

The RMS Lusitania was a UK-registered ocean liner that was torpedoed by an Imperial German Navy U-boat during the First World War on 7 May 1915, about 11 miles (18 km) off the Old Head of Kinsale, Ireland. The attack took place in the declared maritime war-zone around the UK, shortly after unrestricted submarine warfare against the ships of the United Kingdom had been announced by Germany following the Allied powers’ implementation of a naval blockade against it and the other Central Powers. The passengers had been warned before departing New York of the danger of voyaging into the area in a British ship.

The Cunard liner was attacked by U-20 commanded by Kapitänleutnant Walther Schwieger. After the single torpedo struck, a second explosion occurred inside the ship, which then sank in only 18 minutes.  761 people survived out of the 1,266 passengers and 696 crew aboard, and 123 of the casualties were American citizens. The sinking turned public opinion in many countries against Germany. It also contributed to the American entry into the War two years later; images of the stricken liner were used heavily in US propaganda and military recruiting campaigns.

The contemporary investigations in both the United Kingdom and the United States into the precise causes of the ship’s loss were obstructed by the needs of wartime secrecy and a propaganda campaign to ensure all blame fell upon Germany. Argument over whether the ship was a legitimate military target raged back and forth throughout the war, but after the war it was revealed that at the time of her sinking she was carrying over 4 million rounds of machine-gun ammunition (.303 caliber), almost 5,000 shrapnel shell casings (for a total of some 50 tons), and 3,240 brass percussion artillery fuses.

https://en.wikipedia.org/wiki/Sinking_of_the_RMS_Lusitania

The leaders in the American navy however were still determined to contain submarine growth. 

BUILDING NEW SUBMARINES TO DEFEND AMERICAN COAST

By CHARLES P. CALVERT. (August 2, 1915)

The success of the submarine in the present war will shape the naval, programs of all countries in times to come. It has been demonstrated time and again that the greatest battleship is no match for the hidden terrors of the submersibles. Fleets of destroyers may steam round and round a warship or merchantman, but the undersea craft lies in wait and, taking advantage of the first opening, speeds a torpedo at forty knots an hour at its prey. Complete destruction, annihilation in fact is the almost inevitable result.

The United States has learned a valuable lesson from the activities of the German U boats, and the men who plan the American navy are ready to ask congress for an appropriation with which to build thirty new undersea craft in addition to the twenty-six now under construction or provided for. “U” means “untersee,” submarine.

For Defensive, Not Offensive, Work.

The importance of the submarine for the United States not so much for its offensive strength against enemy battleships but for the defense of the coast lines Is appreciated in official quarters. Extensive experiments are now being conducted, and it is expected that when the newest type of submarine is completed it will embody many Ideas that are not generally known.

As an example of this, one may cite the fact that the American navy had installed disappearing guns on the decks of her newest boats. This was kept a secret until announcement came that an English merchantman had been shelled by a German raider. There was no longer any need for secrecy.

The other nations had adopted the same idea and announcement was made that the United States navy was equipped with such boats and guns. Experiments are being conducted to determine the value of electric batteries to propel submarines for submerged operations. It is confidently believed that when the general naval board is ready to make its formal report next month the number of new submarines recommended will depend on the number of batteries and engines, available at that time.

Intelligent Whale Among the First.

As a contrast to illustrate the vast strides that have been made in submarine development in this country one may point to the Intelligent Whale and the Schley. The Whale was built in 1864 in New Jersey by C. Bushnell, Augustus Rice and H. Halstead. She was 28.8 feet long, nine feet in depth and carried a crew of thirteen men. She cost $50,000 and was propelled by hand. In 1872 she was tested and condemned.

The Schley, now under construction, when completed will be able to travel 7,000 miles without replenishing her supplies. Her speed on the surface will be twenty-nine knots and submerged eleven to fourteen knots. She will cost $1,350,000 and will be the most destructive weapon of submarine warfare in the world.

Navy engineers are also hard at .work seeking some effective defense against submarine attacks. While nothing has been revealed. It is assured that questions are being considered that will divide the hulls of battleships into more numerous compartments and stronger bulkheads, so strong in fact that they can withstand the force of the explosion of a torpedo. It is said that the torpedo boat destroyer does not meet the needs in anything like an adequate manner. Location and destruction of submarines by aeroplanes also is considered impractible in any but special cases where weather, depth of water and other conditions make it possible. Bomb dropping from aeroplanes, even over far-reaching land fortifications and other easily visible, stationary objects has not proved so successful as to give much promise where a small dimly visible shape beneath the surface of the water is the target.

Similarity, submarine against submarine is not considered a possible development of undersea warfare unless some new and startling device to give commanders the power of undersea vision is discovered. One of the novel features of the war, however, was the sinking of an Italian submarine by an Austrian submersible. The reports of the encounter were not sufficiently complete to indicate the value of that kind of warfare.

American Navy a Defender.

Officers who advocate the submarine navy say that it is thoroughly practicable for the United States, because the mission of the American navy is to defend the United States from invasion, not to prepare the way for an invasion of any enemy country. That they declare, has always been the theory of the navy department, and they say it accounts for the fact that no great efforts have been made to obtain appropriations for swift battle-cruisers, such as those employed by the British and German navies. Lacking a merchant marine to be protected and being a self-contained nation, fully able to support itself with the resources within its own borders, they argue that battle cruisers have not been considered a necessity to the United States navy, and attention has been concentrated upon getting the greatest possible number of heavy battleships, floating fortresses to defend the coasts. That theory also accounts for the lower speed of American super- Dreadnoughts, it is said, and the greater concentration of gun power in ships of American design compared with similar ships abroad.

With fleets of submarines stationed along both coasts and with navy yards equipped to care for them those officers argue that even the battleships could be spared from the defense line and that no enemy would dare approach with ships and transports a coast well mined and defended with land guns as well as submarines. The risks would be too great, the chances of overwhelming disaster too many.

Grand Forks Daily herald. (Grand Forks, N.D.), 02 Aug. 1915. https://chroniclingamerica.loc.gov/lccn/sn89074405/1915-08-02/ed-1/seq-11/

America was still neutral despite the war drums that were already beating.

But the danger of long range submarines did not go unnoticed.

August 29, 1915

“It is a fact that it would be perfectly possible for a flotilla of German submarines to negotiate the trans-Atlantic passage and maintain itself off our coast by means of secret bases in the West Indies, or even on the very coast of the United States itself by filling its ballast tanks with oil in place of water, at the start of its voyage; by travelling at slow speed on the surface by night, and even by day when no vessels were in sight, it would be possible for one of the largest submarines to reach our coast with a reserve of oil fuel sufficient for several day’s cruising. A submarine base for replenishment of oil supplies would be a very small affair, and it could be snugly located on some unfrequented stretch of our coast, especially in the North; and the refilling of oil tanks could be done at night. It is as well to remember that a surprise submarine attack within our harbors and naval bases is today physically practicable.” From The Scientific American.

THE startling fact has been amply demonstrated that the Germans can send their dreaded submarines across the Atlantic Ocean to the shores of the United States. We need not pay much attention to the report that the German submarines are already using a base off the Maine coast for the purpose of operating against British shipping. The mere fact that they could do so is of vital importance to the United States and should be fully realized by those who wish to protect our coasts against all possible serious war dangers.

Remember that the appearance of a fleet of enemy submarines off our coast with bases of supply to maintain them in prolonged service would mean the stoppage of all commerce on our coasts and in our harbors and the torpedoing of our passenger boats, unless we had the most up-to-date equipment to deal with them.

To meet them we need not only a fleet as large as any other nation, but a large auxiliary fleet of submarines, aeroplanes and fast patrol vessels.

By sending a submarine through hostile waters all the way from Emden, the naval base on the North Sea, to the Dardanelles, a distance of 4,100 miles, the German navy has proved its ability beyond question, to send submarines to New York, a distance practically equal to that already covered.

These vast distances are rendered possible by the revolutionary construction of the new petroleum driven type of German submarine. The water ballast tanks, which are an essential feature of the submarine enabling her to rise and submerge, are filled with petroleum at the start of the voyage. As the fuel tanks are exhausted the petroleum from the ballast tanks flows in and its place is taken by water.

The petroleum engine drives the submarine while it is on the surface, and at the same time accumulates power in the electric engines, which drive the boat when submerged.

Skillful handling of the submarine increases its cruising radius in various ways. Steamships may be engaged or forced to tow the submarine in mid-ocean when out of reach of hostile cruisers in order to economize fuel.

Richmond times-dispatch. (Richmond, Va.), 29 Aug. 1915. https://chroniclingamerica.loc.gov/lccn/sn83045389/1915-08-29/ed-1/seq-38/

On October 10, 1915, Navy Secretary Daniels submitted the President’s formal proposal for naval shipbuilding and an increase in the manpower of the navy and marines.

This five-year program for new construction in the navy and for “increased personnel which the President win submit to Congress this winter was made public last night in detail by Secretary of the Navy Daniels. It calls upon Congress to appropriate this year $217,650,000, an increase of ‘about $65,000,000 over the current naval appropriation.

It asks Congressional approval for a five-year scheme of new construction, munitions, and aviation, with a total cost of $500,482,000.

After long debate Congress passes the Naval Act of 1916 that authorized a $500 million construction program over three years for 10 battleships, 6 battlecruisers, 10 scout cruisers, 50 destroyers and 67 submarines.

For the first time, more money was allocated for fleet submarines than for the smaller and less effective coast submarines.

The new submarine force was finally gaining traction.

Mister Mac