David was readied for college by Joseph Marsh Jr, who had a Latin private school in Braintree, Massachusetts. He graduated from Harvard College in 1766. David studied medicine with Dr Perkins, and settled in Taunton in 1766. He married Eleanor Bradish that same year.
David was a Major General in the Continental Army, an Adjutant and Trusted Loyal Aid to General George Washington, and a Hero of the American Revolution in Massachusetts. 
David was elected representative to the General Court in 1774 and 1789. US Congressman. He was elected to represent Massachusetts's 3rd District in the United States House of Representatives, serving from 1793 to 1795. He also served as a State Court Judge in 1784, David was a member of the Massachusetts State House of Representatives in 1789, Member of the Massachusetts State Senate in 1802, and Lieutenant Governor of Massachusetts in 1809.
By 1796 he had moved to Gouldsborough, having been appointed agent of the great Bingham estate in Eastern Maine. In Gouldsborough he laid out roads, and built wharves, storehouses, saw mills and ships. During this time, he stayed heavily engaged in political duties. The management of the Bingham estate passed to the hands of his son-in-law in 1820. His health not well, he removed to Taunton, to live with his children. His wife, Eleanor, had died in 1808.
In the year 1829, David moved to the Massachusetts General Hospital in Boston. He died there on the 17th of April 1830, and was buried by his wife in Taunton.
In 1777 David joined the Army as a Lieutenant Colonel of the 16th Massachusetts Regiment; serving under Colonel Henry Jackson. In 1785 he was elected Major General of the 5th Division of Massachusetts Militia.
The Maine Historical Society states his birth date was 14 Sep 1748.
It may be possible to confirm family relationships with David by comparing test results with other carriers of his Y-chromosome or his mother's mitochondrial DNA.
Y-chromosome DNA test-takers in his direct paternal line on WikiTree:
Cliff Cobb :
Y-Chromosome Test 27 markers, haplogroup 12b
It is likely that these autosomal DNA test-takers will share DNA with David: