This act she is believed to have revoked in September, but on marrying him, on 9 December 1404, she granted him the earldom for life, the king confirming this on 21 June 1405.

Unlike his father, the Wolf of Badenoch, who had disturbed the peace in the fractious north-east, Alexander, Walter Bower says, "ruled with acceptance nearly all of the north of the country beyond the Mounth".

[6] He achieved this not by using different methods from his father but by his ability to keep his cateran forces in check and to use them to protect his extensive lands when needed; the result was that the areas of Aberdeenshire and Moray were under his control.

Mar had seized his title by forced marriage to the countess following the murder of her husband and Alexander's capture of Kildrummy Castle in Aberdeenshire in 1404.

His possession of the Earldom was later regularized in 1424 by grant of his cousin, King James I. Alexander later married Marie van Hoorn, daughter of Willem, Lord of Duffel, in 1410.