[1] On 7 March 1754, Craik resumed his military career, accepting a commission as a surgeon in Colonel Joshua Fry's Virginia Provincial Regiment.

After the war's end, Craik opened another medical practice at Port Tobacco, Maryland, and on 13 November 1760, he married Mariamne Ewell at her family's estate, Bel Air, located in Prince William County, Virginia.

[3] Washington persuaded him to move his practice to Alexandria, Virginia, where he built his house Vaucluse, where he later died.

[5] Washington summoned Craik out of private practice in 1798 in connection with the Quasi-War against France, installing him as Physician General of the Army on 19 June of that year.

When Washington proved unable to swallow medicines orally, Craik and the other two physicians (Dr. Elisha C. Dick and Dr. Gustavus Richard Brown) treated his condition with bloodletting, the application of various poultices, and a rectal solution of calomel and tartar.

Washington's condition continued to deteriorate, but Craik and Brown decided against Dick's suggestion of a tracheotomy (which might have been lifesaving, but likely would have spread the infection and caused sepsis), and Washington died at 10:10 p.m. Brown and Craik co-published an account of their treatment in December 1800.