But besides his writings and his resistance to the attacks of Arianism, heathenism, or the secular power, St. Ambrose devoted himself to actively defending the cause of the Church and of orthodoxy wherever he had the opportunity. Although the death of Satyrus, a.d. 379, must have greatly added to the troubles of St. Ambrose, he was as watchful as ever against all possibilities of heretical aggression. To his care and opposition to the party of the Empress Justina it was owing that the city of Sirmium was preserved in a.d. 381 from receiving an Arian bishop. And in the same year, when the Arians, hoping for large support from the East, had almost persuaded the Emperor to summon a general council at Aquileia, St. Ambrose prevailed upon him to summon only the neighbouring bishops, and what might have been a serious evil was avoided.