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.
Game unit[]
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An Engineer can fully repair any of your damaged buildings instantly. When sent to enemy buildings, an Engineer can damage or capture it. - Red Alert manual(src)
”
Engineers have two purposes, both of which consume the unit in the process:
To damage or capture enemy structures. An Engineer damages a building by 1/3 of its total health.[1] Depending on the health of the building, it can take up to four Engineers to capture a fully armoured enemy structure. A workaround is to damage the building until it hits red condition,[2] equivalent to 25 % of its maximum strength,[1] and then capture the building. Beware that, according to the source code, "[t]ypically, military or hardened structures such as turrets cannot be captured".[3]
When playing with Aftermath rules, it can take up to three Engineers, with the workaround being damaging the building to 66 % of its maximum strength, as can be seen inside the Mplayer.ini file.
To repair own or allied buildings. The Engineer can instantly "mega-repair" a "friendly or allied" building to full health as long as it isn't a "barrel or mine".[4]
Allied Second World War Arsenal 
Soviet Second World War Arsenal 
