Which battle is credited with beginning trench warfare? Battle of Gallipoli
Battle of Ypres
Battle of the Marne
Battle of Tannenberg

The answer is the Battle of the Marne.

Explanation:

This is because a gap ended up between the German and French lines which could cause the French to flank them so the Germans had to push back. The Allies launched a counter-attack so the German had to dig into positions and the Allies did the same.

sumerians were responsible.

i think its 5! hope i