John Cogswell III led a life of upheaval and controversy. His parents both died when he and his siblings, older sister Elizabeth and younger brother Samuel, were small children. Their mother died first. Then their father John Cogswell, Jr. died on a ship coming back to Massachusetts from a visit to see relatives in England. John was not yet three years old. John and his siblings were placed in the care of different relatives. His sister Elizabeth was placed in the care of their paternal grandparents. John was placed in the care of their paternal aunt Hannah (Cogswell) Waldo and her husband Cornelius Waldo (direct ancestors of Ralph Waldo Emerson). The children's paternal uncle William Cogswell would be their father's executor. This scenario would later lead to a major lawsuit.

Growing up in the household of his Waldo aunt and uncle and their 9 children, John's 9 Waldo cousins, one can imagine John must have felt like the orphan cousin that he was with a step-child syndrome at play. Perhaps this negative permeating circumstance may help explain how John became somewhat of a renegade.

As a young man, it is documented, John was part of a chase after a band of Indians who were causing problems. The Indians then captured John and held him in captivity. Somehow he escaped to tell the story.

John married Margaret Gifford in Ipswich, Massachusetts on July 22, 1674. Margaret was the daughter of Dr. John Gifford of Lynnfield, Massachusetts. Together John and Margaret had 9 children. The children are as follows:

- Margaret (Cogswell) Hawkes (1675-1748) wife of Moses Hawkes with whom she had 5 children.
- Elizabeth (Cogswell) Hawkes (1677-1718) m. Ebenezer Hawkes - 4 children.
- Gifford Cogswell (1679-1752) m. Sarah Parsons - 4 daughters.
- Sarah (Cogswell) Hawkes (b. 1681) married the widower of her elder sister Elizabeth - Ebenezer Hawkes. No children from this union.
- John Cogswell IV (1683-1719) m. Sarah Browne - 4 children.
- Mary (Cogwell) Perkins (1685-1727) m. Jacob Perkins, Sr. - 2 children.
- Bethany (Cogswell) Gott (1687-1755) m. Samuel Gott - 4 children.
- Susannah (Cogswell) Parsons (b. 1691) m. Jeremiah Parsons - 4 children.
- Samuel Cogswell (b. 1693) m. Mary Lufkin - 6 children.

In early 1675 John brought a lawsuit against his Uncle William Cogswell over his father's Estate. This lawsuit was to drag on for years. The lawsuit was known as Cogswell vs. Cogswell. It became highly controversial and much publicized at the time. It turned family members against each other. John's Aunt Hannah (Cogswell) Waldo, who raised John, sided with John's uncle her brother William over John. John insisted on an accounting of his late father's Estate which his Uncle William refused to provide. So John sued. John initially won a judgement against his uncle at court in Salem, Massachusetts for a sizable sum. However, his uncle appealed the court's decision. On appeal his uncle lost again. His Uncle William appealed yet again. The case was overturned later by the high court in Boston leaving John forced to pay expensive court costs. John's father-in-law Dr. John Gifford had fronted John substantial monies to aid him in his legal woes. In the end his father-in-law soured against him too. This affected wife Margaret's inheritance from her father. Her father minimized Margaret's inheritance versus what her surviving siblings received in his Will.

This author/contributor is a direct descendant of John Cogswell III through his daughter Mary (Cogswell) Perkins and her son Jacob Perkins, Jr. Ironically this author is also a direct descendant of John's paternal uncle William Cogswell whom he sued in the famous case Cogswell vs. Cogswell.