He was curate of Christ Church,
St Kilda (1881–83) and Christ Church,
Hawthorn (1883), first vicar of
St Columb's, Hawthorn (1883–94), and Archdeacon of
Gippsland (1894–1902). He was rural dean of
Sale (1896–99), and a canon of
St Paul's Cathedral, Melbourne and examining chaplain to the
Bishop of Melbourne (1899–1902). On 24 February 1902 he was consecrated as the first
Bishop of Wangaratta. During his tenure the bishop's lodge was built,
St Columb's Hall for the education of clergy established and a cathedral partially completed. In 1903 he was awarded an honorary DD by the
University of Trinity College,
Toronto, Ontario, Canada. On Friday, 11 March 1910, Bishop Armstrong dedicated
St Clement’s Church of England Eurobin in the presence of a very large congregation. The bishop was attended by his chaplain, the Rev. G.E. Lamble, Th.L. The Rev. A.R. Noakes, Th.L., and the Rev. J.L. Watt also participated in the service. The Bishop selected Genesis 28:17 for his sermon: “This is none other than the house of God, and this is the gate of heaven.” He retired on 31 March 1927 and became acting incumbent of St John's
Toorak and was president of the
Melbourne College of Divinity in 1930. ==Family==