A subscription database on Ancestry.com of possible interest to those with War of 1812 ancestors:
In the late eighteenth and early nineteenth centuries, Britain routinely removed British sailors who were found on American ships--but those removals sometimes included men who had become naturalized American citizens. The practice, known as impressment, became one of the central causes of the War of 1812.
In an effort to protect American seamen from impressment, Congress authorized the issuance of Seamen’s Protection Certificates, which identified seamen as American citizens. Since citizenship was a requirement, you’ll typically find the place of birth listed and could find naturalization details for immigrants.
For identification purposes, the records also include physical descriptions. Typically age, height, complexion, eye and hair color is given as well as scars and other distinctive physical features.