The conversion of cousins Brigham and Joseph Young to the fledgling Church of Jesus Christ of Latter-Day Saints created a stir and the family gathered at the Rockwood home to discuss this development.

[7] In 1837, Willard Richards and Brigham Young visited AP and Nancy and encouraged them to convert to the "restored gospel".

In 1837, AP traveled to Kirtland, Ohio, at the invitation of Brigham Young in order to meet Joseph Smith firsthand.

[9] Notwithstanding AP came from a leading family in the Holliston, Massachusetts, area, his conversion to Mormonism brought persecution upon him.

Wilford Woodruff reported visiting AP in jail after charges were brought against him due to anti-Mormon prejudice.

In Missouri, AP was a member of the "Danite" organization and participated in the Mormon militia that attempted to defend the saints against mob attacks on their settlements.

He wrote letters home to Holliston describing events in and around Far West that to this date are some of the most reliable historical sources about the nature of the Mormon Danites and the Missouri mob activities of the time.

On one occasion AP received intelligence that an enemy of Smith by the name of John C. Bennett was going to attempt an assassination of the prophet during a drill exercise of the Nauvoo Legion.

As soon as AP was well enough to ride his horse, he was sent by Brigham Young on a mission to collect tithing from the saints on the East coast to help out the financially destitute church.

After fulfilling this mission, AP returned to Winter Quarters where, in 1850, he traveled with his wives and children back out to the Valley of the Great Salt Lake.

[20] In his continuing capacity as a General in the Nauvoo Legion, he was involved in the resistance to the U.S. Army sent out to the Valley of the Great Salt Lake to quell the "Mormon Rebellion.