ch.19 sct.1 C.T.#5

Germany escalated its U-boat attacks in 1917 both out of necessity and because of the pressure of the competion of the times (which led to the necessity of defenses once involved in the war).
Other countries, especially Britain, were building up their naval forces at that time, and Germany didn't want to be overpowered by them, so it started building up its own navy, which encouraged Britain to become even stronger, which in turn, prompted Germany to further build-up, and so on. It became a race for power. Germany had ideals of becoming an empire, and since they had built up this navy, they wanted to use it to help them reach their goal. Then Germany (and its navy) became involved in the war, and Britain blockaded the coast of Germany to prevent the delivery of supplies. Britain also wouldn't allow neutral nations to trade with Germany, so almost all of Germany's supplies, including food, were cut off. They had no choice but to come up with a new plan/tactic with which to overcome Britain's power. Germany's need for a counterblockade against Britain led to the use of submarine warfare. Their navy was much weaker than Britain's, so they needed to be sneaky in their attacks. The submarines, or U-boats, allowed the Germans to do this. In 1917, America joined the Allies, whichprobably contributed even more to Germany's need for submarine usage.
Germany needed to use submarines for attacks in order to overcome the amassed strength of the British navy. This was a time of advancing forms of warfare, and Germany made the advancements necessary for survival by increasing attacks by u-boats in order to defend themselves.