I have no data on the forces of engineers who took part in the Battle of Talavera, but there were some.
I present a colonel of engineers.
The highlight is the purplish hue, which was the colour of the military engineers.
Note the castle embroided on the collar of his uniform, which was the symbol of the corps, as it is now.
Drawing based on a painting by Goya.
Sapper in campaign dress.
Unlike the officer described above, this soldier wears a model 1805 leather helmet, with an apron and a shovel, very nearly the hallmarks of their status as pioneer.
The sword at his side is shorter and thicker than others shown here.
It was used as a knife-machete and an improvised tool.