Category Archives: US In WWI

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Unrestricted Submarine Warfare

Category : US In WWI

Unrestricted submarine warfareuboat-periscope

  • Started by Germany.
  • Major factor leading US to join the war
  • On January 9th, 1917, Germany announced to use the unrestricted submarine war fare.(


Reasons why Germany started this tactic:

  • Germany wanted to swipe Britain away from the war.
  • Germany believed that if the consequences of the unrestricted submarine warfare were shocking enough, America would keep staying away from the war.
  • They believed that America would be afraid of them if they sucessfully cut the vessels of alliances and defeat the British royal navy.


  • Unfortunately this tactic totally provoked America because Germany sank 3 American ships during the unrestricted submarine warfare


Reasons why United States entered the war:

  • Because of the unrestricted submarine warfare (Germany sank 3 American ships).
  • Zimmerman Telegram
  • A telegram sent from German Foreign Secretary in February 1917 aiming to ally with Mexico.u46
  • The telegram tells that if Mexic
    o would like to ally with German, they would help Mexico to recapture land from US.
  • The telegram was intercepted by Britain and British showed it to US.
  • US was extremely angry that they declared war on Germany in April 1917

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Category : US In WWI

U boat is a kind of submarine, which was first used by German naval powers.U-99

  • Germany aimed to cut the vessels of allies through the Atlantic Ocean by sinking merchant and delivering ships to alliance countries.
  • Having naval race with Britain.
  • But once made mistake that they sunk a British ship, which had few American citizens on.
  • Evoked US’s anger and led to the unrestricted submarine war.

(If you want to know further information about the unrestricted submarine warfare, please go the menu and check the unrestricted submarine warfare page.)

February 2018
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