Saint Bertha, born in France in the year 644, was the daughter of Count Rigobert, who served in the court of Clovis II, and Ursanna, daughter of the king of Kent in England. In the twentieth year of her age this beautiful and pious maiden was married to the cousin of the king, the noble Sigfried, who determined to advance with his spouse along the paths of Christian perfection. They were blessed with five daughters, of whom two died in infancy; two others, Gertrude and Deotila, are canonized Saints like their mother.
After several years of the most harmonious union, Sigfried died in 672, and Saint Bertha took the veil in a monastery which by divine instructions she built at Blangy in the district of Artois. The monastery was solemnly consecrated in January of the year 682, and the holy widow endowed it with her terrains. Her daughters Gertrude and Deotila, greatly impressed by their mother's act, soon followed her example. She was persecuted by Roger, or Rotgar, a young lord of the court of King Thierry III, who was furious over her refusal to give him Gertrude, already a professed religious, in marriage. He endeavored to slander her mother as being opposed to the succession of Thierry and involved with the English royalty in a conspiracy. The King sent for the Abbess to defend her cause, not sure that such conduct could be attributed to this holy woman. He took her in fact under his protection, and the persecution was halted.
On her return to Blangy, Bertha had three churches built, to honor Saint Omer, Saint Vaast, and Saint Martin of Tours, and completed the construction of her convent. And then, after establishing the Rule of Saint Benedict and a regular observance in her community, she named Saint Deotila to replace her as abbess, and retired to a solitary cell to spend the remainder of her days in prayer. At the age of 79, having already buried her two daughters Deotila and Emma, she left Gertrude as Abbess in the monastery of Blangy, and died peacefully in the year 723.
Les Petits Bollandistes: Vies des Saints, by Msgr. Paul Guérin (Bloud et Barral: Paris, 1882), Vol. 8; Little Pictorial Lives of the Saints, a compilation based on Butler's Lives of the Saints, and other sources by John Gilmary Shea (Benziger Brothers: New York, 1894).