Plz be serious with this one. I would really appreciate it. List 5 significant events from World war I

I need
-the date
-the event
-signifance

Hello,

Sep 15, 1916
First Tanks
The British employ the first tanks ever used in battle, at Delville Wood. Although they are useful at breaking through barbed wire and clearing a path for the infantry, tanks are still primitive and they fail to be the decisive weapon, as their designers thought they would be.

June 28, 1914
Archduke Assassination
Archduke Franz Ferdinand is assassinated in Sarajevo. His death is the event that sparks World War I.

May 7, 1915
Lusitania Sinks
A German submarine sinks the passenger liner Lusitania. The ship carries 1,198 people, 128 of them Americans.

Sep 15, 1916
First Tanks
The British employ the first tanks ever used in battle, at Delville Wood. Although they are useful at breaking through barbed wire and clearing a path for the infantry, tanks are still primitive and they fail to be the decisive weapon, as their designers thought they would be.

Feb 25, 1917
Zimmerman Telegram
British intelligence gives Wilson the so-called Zimmermann Telegram, a message from German foreign secretary Arthur Zimmermann proposing that Mexico side with Germany in case of war between Germany and the United States. In return, Germany promises to return to Mexico the "lost provinces" of Texas and much of the rest of the American Southwest. Mexico declines the offer, but the outrage at this interference in the Western Hemisphere pushes American public opinion to support entering the war.

Use the formula: (n-2)×180, where n is the number of sides(18-2)×180= 28800, now this is the full exterior angle of 18-gon so you divide it by 18.28800÷18=160