Engineers are one of five officially designated non-combatant infantry units that can be trained by a commander (the others are the Medic, Thief, Field mechanic and the spy used in Command & Conquer: Red Alert 2). Although Engineers possess decent armour, they are normally unarmed, relying on commanders to clear the battlefield for them, or more likely, to be transported in APCs, latter IFVs or in helicopters. Engineers were normally used for three purposes:
Cannonball! - Allied Engineer, approaching to water in RA3
1. To capture enemy structures. For this, an Engineer was trained to be familiar with the standardized computer equipment present in most structures, particularly the master control terminal. The most highly trained engineers memorized blue prints of the structures, and then used small explosive charges to break their way in. During the Great World War II, it would take five Engineers to break into a fully armoured enemy structure, but if it were damaged it could take less. By the Great World War III, this was overcome by superior training and better explosive charges. These engineers were capable of taking over enemy structures almost instantly, but there was a price tag attached: these engineers cost over 4 times the price of a basic infantry. The Engineer was required to stay at the MCT and operate the structure from that point onward, but this did not prevent rival engineers from attempting to recapture the structure. The vast majority of the time, the Engineer was busy operating the structure, and didn't notice as a rival engineer would sneak up on him and remove him from the picture, then operating the structure himself.
2. To repair bridges. This was developed by the time of the GWWIII. Engineers realized that they would have to repair bridges - floods and other problems, as well as enemy forces' destruction of the bridges, often was problematic. Fortunately, most bridges stored all of the tools for their own repair, except for a few the engineer carried, which allowed the Engineer to repair bridges very quickly. Unfortunately, the Engineer used up most of his supplies and tools in this way. Rather than journey out onto the battlefield without tools - and therefore without the ability to repair structures or capture structures, Engineers wisely decided to stay inside the bridge repair hut - ostensibly to make sure that the bridges would not be damaged again, although in practice they were helpless to intervene should the bridge be destroyed - it would take another engineer to fix it again.
3. To repair that sides' own buildings. Again, the Engineer would go in, and use similar tools to the bridge repair hut to fix the structure. Again, these tools and supplies would be used up in the process, and the Engineer would wisely choose to stay in the structure.
Engineers can deactivate Crazy Ivan's bombs thanks to their special pyrotechnic training. Once the bomb is active, an engineer may be requisitioned to disable it. This action does not "waste" the engineer and he is fully-prepared to perform other duties.
Additional equipment given in War of the Three Powers
As a result of buildings that can be built over water All engineers are amphibious to capture ports.
Allied Engineers were given medical equipment and easy to set up tents used for patching up wounded soldiers, along with a collapsible jet-ski which can be used to cross large bodies of water.
Soviet Engineers were given basic construction tools which could be used to build a Battle Bunker (if the player pay him 500$), a pistol for use in self-defense and an inflatable raft for crossing water.