Not 100% sure what you're asking here - what country, what war, etc.

My only attempt at answering your question (assuming a 20th century war), is yes, engineers were involved in the war effort, and could receive exemption from active fighting. Many were sent just behind the lines to repair/build tanks/trucks/weapons (talking artillery not rifles), others were at home working in factories designing/building other war weapons/vehicles. And more still, some were training soldiers so that they were able to repair cars/weapons on the go.

One personal example of this was my great-grandfather who was called up by Canadian conscription in WWII. He was an electrical engineer. They called him out of his training program which was to be sent off to fight the Japanese and was moved to a military training base here in Canada where he taught certain recruits how to fix their cars/trucks out in the field.