Born Agatha LeVigne in 1804 in the Mackinac area, she was the daughter of an Ottawa woman and a European father. Her mother married Joseph Bailly in 1818. Agatha was very beautiful and fair for an Indian woman. Edward Biddle came to the Island from a wealthy and influential Philadelphia family to make his fortune in the fur trade. He became attached to Agatha and they were married in 1819. Similar to Josette LaFramboise's wedding, it was the event of the season. Agatha was married in a traditional Indian outfit. It consisted of a skirt ornamented with ribbon and beads, leggings, a silk blouse with fitted sleeves around the arms and wrist and covered with necklaces. Three other women wore similar outfits - her mother Agatha Bailly, Madame LaFramboise and Madame Schindler. Agatha would live her life wearing traditional Indian clothes. Her home on Mackinac Island still stands and is maintained by the Mackinac Historic Parks Commission.
Of this marriage, three children were born: Sophia, John and Sarah.
Agatha was the chief of a group of people that consisted of 66 families or 168 people in 1870, of which all, with the exception of 2, were headed by women. This 'sub-band' of the Mackinac region contained half blood women who married white husbands, and their children. The chiefs of the area determined that the individuals in Agatha's band were entitled to monies due the local indians from the 1836 treaty. Annuities were paid to Agatha by the govermnent and she distributed the funds according to the stipulations in the treaty.
While Agatha is different from the other women in this group in that she worked with her husband in the trade, her presence is important. There are records of her request for restitution from the government under the Treaty of Washington (1836) that demonstrates her assistance to Indian people. There ae several letters attesting to Mrs. Biddle's generosity to the Indians in the same records, one of those is transcribed here. Also, her position as chieftaness suggests a respected place among the metis and Indian people on the Island.