In use from 1638, until 24 October 1790; and from 1814 to 1830. This ensign, plain white on most ships, could sometimes be found white Semy-de-lis Or. The ceremonial of salute was very strict - disrespectful salute from a foreign ship would mean battle: any ship encountering a King's vessel at sea had to dip her flag, if hoisted at the main mast, and/or her ensign, lower her fore sail and take the lee gage.

Pierre Gay, 19 October 1999
Source: Encyclopaedia Universalis, Thesaurus-Index, pp. 1111-1112

The best known of the British Maritime flags, or Ensigns, which were formed by placing the Union flag in the canton of another flag having a field of white, blue or red. This flag is also known as the Meteor flag, and was widely used on ships during the Colonial period. This was the first National flag of the United States.