advance guard

See also: advance-guard

English

advance guard (plural advance guards)

A unit or units leading the way of advancing or marching troops, guarding them from ambushes, reconnoitering and pursuing the enemy, etc.
An individual soldier in the same role.

Every precaution was taken; and in some of the denser portions of the jungle they regularly felt their way with advance guards and flankers, who, poor fellows, had a most tough job to force their way through the tangled creepers and undergrowth. — G.M. Fenn, "Middy and Ensign", 1883.
Each attacking column was divided into three parts, a forlorn hope of twenty men leading, which was followed by an advance guard of one hundred and twenty, and then by the main body. — Theodore Roosevelt, "Hero Tales From American History", 1895
My native land is one of those rugged isles which form the advance-guard of Scotland in the Northern Ocean. — R.M. Ballantyne, "The Crew of the Water Wagtail", 1875

leading unit of an army

an individual soldier in the same role