[4][5] William Mann signed the 1640 Providence Agreement which established the first secular, representative government in America.

In 1641, he and twelve others signed a letter asking Massachusetts Bay Colony to intervene after the followers of Samuel Gorton caused a riot.

From some neighbors and the widow Mann herself, I understand, that notwithstanding her motherly affection, which will make all burthens lighter for her children's good, yet she is not without fears, that if the town be not favorable to her in after times, some hard measure and pressures may befall her.

My request is, therefore, that it would please you to appoint some of yourselves to review the will, and to consider whether the pains of the father, deceased, or want of time, hath not occasioned him to leave some of his purposes and desires imperfect, as also to propose to the town wherein, according to the rules of justice and mercy, what the deceased intended, may be perfected, for the greater comfort both of his widow and orphans.

After the war, Frances Mann joined her daughter, Mary, and son-in-law, John Lantham, in Dartmouth, Massachusetts.