XWuZHeAR

Yes and no. They were primarily used during World War I because during that time, Trench Warfare was the typical type of fighting you saw in most of the world. Armies would spend days and weeks building trench lines, all connected by other trenches called Saps, that would allow people to move about protected from the line of fire, except mortar rounds, and they could hold of enemies with few numbers. Because of the fact that Mortars had to 1. be above trench lines to prevent accidental detonation in the trenches (They could literally shoot the side wall of their own trench) and 2. A spotter or team of spotters were needed to help aim the mortar, being far out in the field, trench warfare made it difficult to be assaulted properly with a mortar because those in the trenches would pop out and shoot the spotters, or worse, the mortar cannon or ammunition.

A second reason for trenches was because they could be well hidden in a lot of terrain and would cause similar ambush issues. So, to combat enemy trenches, the German army trained specialized troopers who were armored and trained to literally get into the trenches by multiple means, and would storm them, gunning down anyone they saw, burning the bunkers with flamethrowers, and detonating charges to collaps saps and trenches, thus cutting off whole sections of trench networks from supplies. They were first called Shock Troopers, then Storm Men, then Storm Troopers as time went on. Due to the advancement in ballistic projectiles, tanks, and aerial warfare, Trench warfare fell into less use in some parts of World War II, specifically the African campaigns between british and German forces, and any regions with mountainous terrain, as a good spotter on any slope could see a trench and mark it for aerial bombardment.

Yup and I want to become a navy pilot someday, even if trench warfare is no longer a thing given the choice who the hell would choose infantry?

Well, your from the US, I would assume you may have atleast heard of the ASVAB. It is a test administered to High School students that is composed of many different subjects and is used as a placement test for military branches. 9 times out of 10, people who place low in the ASVAB do not go far in most military branches. This is not due to lack of intelligence or anything. It's more of a statistics thing. Another reason is that some of the more illustrious military organizations such as the Green Berets, Ranger Corps, Marines, and Navy Seals require a lot of testing, aptitude, and high marks in a military career. Because of this, many people choose to go into the Army, National Guard, or Navy because they have the ability to go in under the basic career line, get things like tuition reimbursement, skill and tradesmen vocations, and so forth for signing a tour of duty roster. For National Guard it is 2-4 off duty and 2 on active duty. That was of course back in 2007 when most of my highschool mates joined.