Basically, since the invention and more widespread use of the submarine, there were certain rules of warfare regarding them. Submarines, when they wanted to sink a ship (when it wasn't an obvious military ship), were supposed to pop up out of the water so that the ship could see them; then someone from the submarine was expected to tell the ship that the submarine was going to sink it. The submarine had to give the other ship time to evacuate the crew to lifeboats and get a safe distance away. Once all that was done, the submarine was allowed to sink it.
Obviously, that doesn't work well when you want to get stuff done fast. Germany's navy was far smaller and weaker than Britain's; throw in France's and those of other countries, and Germany was at a considerable disadvantage. Germany needed to be able to hit hard and fast without having to slow down if they wanted to have any chance at defeating the Allied navies.
So unrestricted warfare was basically ignoring those old-fashioned rules. They began sinking ships without warning, meaning crewmen were getting killed, and the whole ship was lost. German subs would sometimes accidentally shoot neutral ships, like those belonging to the US, or shoot ships carrying people from neutral countries (like the British cruise ship, the HMS Lusitania, which had over 100 Americans on board when the Germans sank it).
Germany agreed to stop unrestricted submarine warfare after the Lusitania incident, because they didn't want the US to join the Allies. But in early 1917, they decided that they couldn't keep that up, and had to restart it. This, coupled with their attempt to secretly convince Mexico to declare war on the US, angered the Americans enough that they declared war on Germany in April 1917.
In WW1, the German policy of unrestricted submarine warfare irritated neutral nations such as the United States and eventually helped public opinion to support the US entry into the war. In WW2 the German policy of unrestricted submarine warfare in the Atlantic irritated nominally neutral nations such as the United States and provided a rationale for increasing US support of Britain and its allies. In WW2 the American policy of unrestricted submarine warfare in the Pacific probably contributed to the degradation of Japanese economic capabilities as the war progressed.
During World War I, Germany's goal in returning to unrestricted submarine warfare in 1917 was, quite simply, to bring the long war to a quick end. Realizing that this decision could bring war with the United States, German leaders calculated that their submarines would end the war before American involvement could make a difference.
From what I can see, Germany's unrestricted submarine warfare policy, and the sinking of two american ships without warning is what motivated America to go into the war. Once again this is from what I can see on google lol.
Unrestricted Submarine Warfare. This German policy promised that any ships bringing supplies to the British Isles would be sunk by u-boats and was the only one of Germany's strategies that left the battlegrounds, thus the only one which threatened America.
In 1916 the Germans attempted to "bleed France white" at Verdun and lost the battle after both sides lost a lot of soldiers. And 1917 saw the adoption by the German high command of the unrestricted submarine warfare policy. Shortly after, the US declared war on Germany.
it referred to sinking ships
Unrestricted Submarine Warfare.
Order of events that describes changes in Germany's policy of unrestricted submarine warfare:unrestricted submarine warfareAmerican ultimatummoratoriumcancellation of the Sussex Pledge
This policy was called unrestricted submarine warfare
Serbia
announced its policy of unrestricted submarine warfare
In WW1, the German policy of unrestricted submarine warfare irritated neutral nations such as the United States and eventually helped public opinion to support the US entry into the war. In WW2 the German policy of unrestricted submarine warfare in the Atlantic irritated nominally neutral nations such as the United States and provided a rationale for increasing US support of Britain and its allies. In WW2 the American policy of unrestricted submarine warfare in the Pacific probably contributed to the degradation of Japanese economic capabilities as the war progressed.
To cut Britain, Europe and Russia off from deliveries of badly needed supplies.
Unrestricted submarine warfare (in the Atlantic).
the Zimmerman telegraph, Germany shooting down the Lusitania that had passengers on it and Germany's policy of unrestricted submarine warfare.
The German policy of unrestricted submarine warfare against shipping. This led to the sinking of the Lusitania in 1915. Great Britain and France were major trading partners.
"Unrestricted Submarine Warfare" was the policy followed by the German Navy to have German submarines without warning sink ships that were transporting food and other resources. U-boat was a term in WW1 referring to a submarine.