My Great-great grandfather was in WWI, and while I didn't know him, I did want to learn more about what killed him. There are so many types of weapons that were utilized in WWI; even more than just WWI guns.
Of course, they used guns, but they also used flamethrowers, mortars (which are mine-throwing guns), tanks to destroy large areas, and poison gases. Besides rifles, they used machine guns and heavy artillery to destroy each other. They utilized airplanes and submarines for their attacks, killing thousands of people in just four short years.
A WWI tank.
Soldier using a flamethrower in WWI.
“My Great-great grandfather was in WWI...”
A WWI mortar.
WWI invited mustard gas, so they needed to invite gas masks, too.
Soldier with machine gun and also wearing a gas mask.