What sapper mean?

Answer 1

What are Sappers?

Sappers of the Dark Ages were often men or teams of men who worked to tunnel into keeps during seiges. They employed a number of tactics, from attempting to enter into the keep's courtyard, to simply collapsing keep walls. Often, they would tunnel under sections of keep walls and start fires there, in hopes to collapse a section of the wall above it, so that major offensive groups, such as light infantry or bucklers could enter into the keep and battle to take it. Modern sappers employ similar ideals to breach perimeters of bases, or forward posts, for purposes of military advancement. Modern sappers may also be known as perimeter infiltrators, or advanced party defense probes, though in full battle, their intent remains the same as in ancient times - that being, to open a breach in a wall or fort, so that main-body-troops can enter to overtake tactical targets.

Answer 2

Answer

Sapper or Pioneer were early terms for engineers or soldiers who helped clear roads or construct fortifications in the field in early 1800's. They did not do heavy construction as Engineers were later formed to do this.

The British Army still has a job title of Sapper during WW2 and maybe today.

Today a number of countries have soldiers called sappers performing tasks such as Combat engineer. They build stuff, clear mine fields, demolition etc.