All 3 Uses of

advocate
in
1776, by McCullough

"Every brutal gratification can be so easily indulged in this place," wrote William Tudor of Boston, Washington's judge advocate, to his fiancee, "that the army will be debauched here in a month more than in twelve at Cambridge."†
p. 125.5 *

advocate = a lawyer or officer of the court in some jurisdictions in Europe, colonial America, and the military

Captain William Tudor, the judge advocate, described the whole army as impatient for action.†
p. 153.3

On December 24, the day before Christmas, Washington's judge advocate, Colonel William Tudor, who had been with him from the beginning, wrote again, as he often had during the campaign, to tell his fiancee in Boston of his continuing love for her, and to explain why his hopes of returning soon to Boston had vanished.†
p. 271.3

Definitions:

(1) (advocate as in: to advocate)
to recommend or publicly support (someone or something)
(2) (advocate as in: an advocate supporting)
a person who publicly supports and works to advance a cause

or more rarely:

someone acting in the role of a defense lawyer in England's past and in some jurisdictions today
(3) (advocate as in: an advocate in court)
a lawyer or officer of the court in some jurisdictions in Europe, colonial America, and the military
(4) (devil's advocate as in: I'll play the devil's advocate)
a person who takes an unpopular position to encourage debate or test ideas