The Order of the Knights of Pythias, an international non-sectarian fraternal order, was founded in Washington, D.C. in 1864 by Justus H. Rathbone. It was the first fraternal order to receive a charter from the United States government under a special act of Congress. The order's primary objectives -- to promote friendship and to relieve suffering -- are supported by its distinguishing principles of friendship, charity and benevolence. Both the national flag and the Bible have an important place in lodge rituals.

Interest in the Knights of Pythias spread rapidly, and by the turn of the 19th century hundreds of lodges had been established in the United States and Canada. Apparently Marysville Lodge No. 18 was functioning as early as 1905; however, its by-laws were not formally approved until August 1928. Marysville Lodge supported a number of charitable causes and established a widows and orphans' fund to assist members' families. Wines and liquors were excluded from lodge functions and gambling was forbidden in lodge rooms at Castle Hall.

The Knights were active elsewhere in the Maritimes. By 1935 lodges had been established at Milltown, St. Andrews, Moncton, Woodstock, Juniper, Campbellton, Sackville, Saint John, Sussex, St. Stephen, and Fredericton in New Brunswick; at Sydney, Halifax, Windsor, Parrsboro, Amherst, Oxford, Port Grenville, and Truro in Nova Scotia; and at Charlottetown, Prince Edward Island. Most of these lodges, including Marysville Lodge No. 18, were affiliated with Grand Lodge Knights of Pythias Domain of the Maritime Provinces. Marysville Lodge No. 18 was functioning in 1954.