Branch No. 1 in Thunder Bay had a rather unusual beginning. Unlike other branches which were formed in Canada by combatants once they settled here, Branch Nr. 1 was organized by former Polish soldiers en route from Halifax to Thunder Bay (formerly Port Arthur and Fort William). Two groups of combatants (groups 7 and 8) arrived in Halifax on board HMS "Robin" on November , 1945, and were directed to Port Arthur and Fort William, commonly referred to as "The Lakehead." One group was under the command of Bronislaw Sobolewski, the other under Jan Adamski. Both groups were first taken to a holding area in Winnipeg and housed in military barracks. It was there that they held the founding meeting on November 18, 1946, attended by 74 combatants, and chaired by Mr. Boleslaw Czubak. The first group of 106 combatants to arrive in the Lakehead received a warm and friendly welcome from the local Polish community. Members the community helped them find housing and settle in, which the combatants appreciated greatly.Mr. Niedbaly, who owned a large house, invited any of the combatants to live there free of charge until they found suitable accommodations.

Initially, the branch held its meetings on the premises of the Jozef Pilsudski Fraternal Aid Society and the Polish branch of the Royal Canadian Legion. With the support of Colonel Evans and Major Wilson, the first executive board applied for and then received the Charter of the Royal Canadian Legion on May 16, 1948. Thus Branch #1 became Polish Combatants' Branch "Lwow" #219 of the Royal Canadian Legion of the British Empire Service League. This was very important for the branch since, as a branch of the RCL, it enjoyed access to benefits not available to other branches of the Association. Activities, such as picnics, banquets and dances, organized by the branch not only provided an opportunity for the combatants to socialize but also brought in revenues, which the combatants planned to use to purchase their own building.

The first picnic was held on Mr. Jan Bialoskurski's farm. On August 17, 1948 the branch held a banquet to celebrate its new charter. Another banquet was held on October 20, 1948 to celebrate the end of the combatants' two year contracts. The mayor of Port Arthur and federal MPs attended the banquet for the first time since the branch was established. The branch opened a library with books it received mostly from England. It was first located in the house of the branch secretary, Mr. W. Kwasniewski. Later, the library was housed on the premises of the Polish Veterans' Fort William branch. Branch meetings were held in the Croatian hall and on the premises of the Fraternal Aid Society. The executive met at the house of Mr. Kwasniewski. From 1949 to 1955 the branch rented a basement room at the Royal Canadian Legion, where the executive board held its meetings, paying a monthly rent of $10.00. Lack of space seriously hampered the activities of the branch and the combatants felt that something had to be done to improve the situation. The branch initiated talks with Group #19 of the Polish Alliance of Canada hoping to jointly build a community centre. Four years later, a verbal agreement was reached and a joint building committee formed. Unfortunately, Group #19 opted out of the agreement and started construction on its own. Branch #1 had to rely on its own resources. It already had some money saved, and to earn more, decided to screen Polish movies. Initially, it borrowed a projector, but later bought one.

In 1949, the National Executive Board of the Association was moved to Port Arthur, which made it possible for branch members to hold office on the Board. At the time, Mr. Kazimierz Klimaszewski was the national president, Mr. Waclaw Kwasniewski the secretary and Mr. Jan Syposz the treasurer of the National Board. On January 13, 1952 the branch was visited by General M. Karaszewicz-Tokarzewski who was invited by the Canadian Women's Club to present a lecture. The General met with members at Mr. Kwasniewski's house. (Other important guests included Karol Ziemski, President of the World Federation of Polish Combatants' Associations in 1965, General S. Kopanski in 1971, Kazimierz Sabbat, Premier of the Polish government-in-exile in 1985, and the Polish National Ski Team, attending the World Skiing Championship, in 1995).

In 1953 the branch purchased two lots from the City of Port Arthur for one thousand dollars. Work on construction of a building, mostly by the combatants themselves, started almost immediately. A fund-raising campaign was initiated to cover the initial costs of construction. In two years, the combatants finished the exterior of the building, which had a spacious basement where the branch planned to have a bar. A license to sell beer was obtained from the city. To increase the building fund, the branch also held Sunday dances on the farms of Mr. Sojka and Mr. Czaban. The new building was officially opened on November 12, 1955. By 1958 the branch had its own colours as a branch of the Royal Canadian Legion. On October 23, 1961, the branch received its colours as an Association branch. The colours were presented to branch president, Mr. F. Telpuk, by General Wladyslaw Anders. In return, the combatants presented the general with a Port Arthur coat of arms with "SPK" inscribed on it. The coat of arms also bore an inscription: "To the Commander of 2nd Corps from Branch #1 of the Polish Combatants Association in Port Arthur." The mayor of Fort William made the General an honourary citizen of the town. New colours, made by sisters in a Krakow monastery, were presented to the branch in 1994. The activities of the branch increased. The Ladies Auxiliary was formed in 1953, with 32 members having joined by 1962. In 1963, together with Group 19 of the Polish Alliance of Canada, a Youth Section was formed.