A Catholic and a Jacobite, Browne, like several of his other relations, sought scope for his ambition in a foreign military career (Flight of the Wild Geese).

In recognition of this special service Browne was raised by Anna to the rank of major-general, and in this capacity accompanied General Lacy on his first expedition to Finland.

Browne's fortunate diversion of the enemy's attacks at Kolin, 18 June 1757, contributed materially to the allied victory, and in token of her appreciation of his conduct on the occasion Maria Theresa presented him with a snuff-box set with brilliants and adorned with her portrait.

At Zorndorf, 25 August 1758, he again distinguished himself in a similar manner, his opportune assistance of the right wing at the most critical moment of the battle changing almost inevitable defeat into victory.

He was confirmed in the office under Catherine II who granted him Smiltene Manor, and for thirty years to the close of his life administered its affairs with remarkable practical sagacity, and with great advantage both to the supreme government and to the varied interests of the inhabitants.