inroad

An advance into enemy territory, an attempted invasion; an encroachment, an incursion.

[…] That ſince that time he [Archibald Douglas, 6th Earl of Angus] was become the ſubject of King Henry [VIII] of England, his Majeſty's [James V of Scotland's] greateſt enemy; and was now the cauſe of all the Inroads made by the English into Scotland: […]

[A] child knowing the heate of fire, will as readely iudge of the perrill, as the wiſeſt Senatour, of the inroad of a borderer, or the politick captaine, of the vnequall encoũter with his enimy, […]

Often followed by in, into, or on: initial progress made toward accomplishing a goal or solving a problem.

Three weeks into it, I am finally beginning to make inroads on this project.

You must have been fairly surprised at Dr. Glaser's inroads into reprogramming the brain.

To make advances or incursions.

[Y]ou muſt not expect him to go with you, inroading or making incurſions into Georgia; for he is an Armenian, true to his faith; and not a Georgian, falſe and diſtruſtful!

[T]his is the first war that has befallen in my time, and no inimy has yet inroaded far enough into the Colony, to be reached by an arm even longer than mine.

To make an inroad into (something).

[Y]ea, the Saracens had lately waſted Italy, conquered Spain, inroded Aquitain, and poſſeſſed ſome iſlands in the mid-land-ſea.

The kyngdom of Heven be Chriſt, 'teys reſembled to this noble kyng / With riches inroded mercy for to lern, and to have compaſſion. / One of another, after goddes Faſſyon.

A barangay of Aurora, Zamboanga del Sur, Philippines.