During the Napoleonic Wars and earlier, the European armies had designated a special soldier called a sapper, who carried an axe to clear roads through heavy woods. Later, engineers were added, who were more specialized troops that could build bridges and observation towers.
The Imperial Guard were the special fighting soldiers that protected Napoleon and his palaces. The Imperial Guard did not have any Engineers. After a fire in his palace in 1807 (I believe), a decree was issued to organize the Engineers of the Guard.
They wore a very similiar uniform as the Foot Artillery of the Guard: blue coat with long tails in red and red turnbacks and black lapels. Usually, they wore black leggings. But instead of a bearskin fur cap, the Engineers of the Guard wore an unusual steel helmet with a black crest. (Cavalry wore either bronze helmets or steel helmets with horse hair "tails").
The Engineers of the Guard were a small unit and in the field, they usually built observation towers for Napoleon to view the battle.
See this link for more history.
http://xoomer.virgilio.it/jmurat/uniformi/geniere1.htm
Actual photo of Engineers of the Line(not the Guard). The Engineers of the Line wore a shako hat, similiar to the Artillery of the Line. These photos are the only surviving images of veterans of the Grande Armée and the Guard actually wearing their original uniforms and insignia they wore in 1815 Waterloo Campaign.
http://www.brown.edu/Facilities/University...ans/Lefebre.jpg
