This is a special prayer form that is used for Memorial Day. It comes from the Book of Common Prayer, page 488.
Almighty God, our heavenly Father, in whose hands are the living and the dead: We give thee thanks for all thy servants who have laid down their lives in the service of our country. Grant to them thy mercy and the light of thy presence; and give us such a lively sense of thy righteous will, that the work which thou hast begun in them may be perfected; through Jesus Christ thy Son our Lord. Amen.