During the American Civil War from 1861–1865 the Union Army established a headquarters in Davenport. There were five army camps in the city and four of them were within St. Margaret's parish boundaries. Undoubtedly, this affected the parish and the pastor's ministry. After the war an addition was made to the church building in 1866 forming a wing on the right side of the original church structure. The 1860 building on the left side was also incorporated into the church. An unusual feature of the church was that the roofline of the addition was higher than that of the original church.