In 1919, the Historic Sites and Monuments Board of Canada recommended that the ruins of Fort Cumberland be preserved, given their historic significance. An area of 59 acres was designated as a national historic park by the government in 1926. The original name, Beauséjour, was used and the park became one of the first historic sites in Canada.

Dr. John Clarence Webster was the first person to bring the historical significance of the Beauséjour- Cumberland region to the attention of the public and government officials. He was a surgeon and gynecologist of international renown who, after his retirement in 1919, lived in Shediac, his native town.

He devoted considerable energy to the identification and restoration of various historic sites in the Maritimes, including the fort at Beauséjour, the habitation at Port-Royal and the fortress at Louisbourg. He also founded the New Brunswick Museum in Saint John. Dr. Webster wrote numerous historical works on the Maritimes and was a member of the Historic Sites and Monuments Board from 1923 until his death in 1950. He became chairman of the Board in 1944.

The Museum at Fort Beauséjour / Fort Cumberland was officially opened in 1936. The Webster wing, housing hundreds of artefacts collected by Dr. Webster in both New Brunswick and Nova Scotia, was opened in 1949.