Dacre's military career began in 1382 in Scotland, where he was knighted while serving under the banner of Richard le Scrope.

[2] He was part of Richard II's invading army during the 1385 punitive expedition into Scotland.

Dacre was called to give a deposition in the celebrated case of Scrope v Grosvenor.

[2] He testified in favour of Scrope, and against Sir Robert Grosvenor.

[a][3] Their son, Thomas succeeded to the barony upon William Dacre's death in 1398.