I was just thinking of my Father’s WWII service. He was in the combat engineers.
There were times when they were at the tip of the spear, such as clearing mines. They also were often the last ones to retreat, blowing bridges, etc.
Kampfgruppe Peiper failed at the Battle of the Bulge because of the American combat engineers, and its commander, Joachim Peiper, knew it.
My father was in the Combat Engineers. They would be routinely sent out as commandos on suicide missions, forging well beyond the front lines to fight the Germans and secure river beachheads, where they would build the bridges for the infantry to use when the front line caught up with them.