Combat Engineers are often described as 'Force Multipliers' because they enhance the survival of regular troops. In the US Engineer Soldiers Handbook (Field Manual 21-105 issued June 1943) it goes further, telling new engineers... "You are going to make sure that our own troops move ahead against all opposition, and you are going to see that enemy obstacles do not interfere with our advance". While this may mean building bridges or laying communication lines, there are also combat tasks that need to be performed that require an engineer at the tip of the spearhead.
Chapter 9 of the Handbook is entitled Assault of a Fortified Position and describes how multiple teams of engineers can work towards fixed enemy positions to destroy them. Brevity must have been the order of the day when writing this chapter because it consists of two short pages. Reading it you are left in no doubt that some of the duties of a combat engineer were highly dangerous.
"A typical prepared defensive system of fortifications consists of a number of mutually supporting strong points, such as concrete emplacements called 'Pill-boxes'. The best way many of these can be destroyed is by foot troops armed with special weapons. It's a difficult combined-arms job to which engineers are often assigned. It requires aggressiveness, skill, speed, teamwork, courage, and determination."
These models by Peter Pig are carrying M2 Demolition Satchel Charges. In the post-war period they were called M37 Demolition Charges but these later versions used C4 (not invented until 1956) while the second world war versions were filled with eight blocks of TNT. They included two priming assemblies and a 'ripcord' type pull igniter. Try as I might I haven't been able to find out what the timer length was on these (if you know, please leave a comment below) although I imagine it could be set by the engineer depending on how it was being used.