Which war began the modern era?
world war i
the american civil war
world war ii
the chinese civil war

The correct answer is A) World War 1.  

The war that begun the modern era was World War 1.  

World War 1 was the first great war of the century. This was a global event that initiated on July 1914 until November, 1918. It was one of the largest, bloodiest, and deadliest conflicts in history of humanity. Historians believed that it mobilized almost 70 million military people. The battle was fought by two sides. One side was the alliance called the Triple Entente, formed by Russia, France, and Great Britain. The other side was the alliance called The Triple Alliance formed by Germany, Italy and Austria-Hungary. Eventually the Triple Entente won the war but a high cost.

when world war i broke out across europe in 1914, president woodrow wilson proclaimed the united states would remain neutral, and many americans supported this policy of nonintervention. however, public opinion about neutrality started to change after the sinking of the british ocean liner lusitania by a german u-boat in 1915; almost 2,000 people perished, including 128 americans. along with news of the zimmerman telegram threatening an alliance between germany and mexico, wilson asked congress for a declaration of war against germany. the u.s. officially entered the conflict on april 6, 1917.