Description: This paper is from Transactions of Society of Actuaries 1955 Volume 7, Number 17. The authors note that ‘mortality experiences of large closed groups carried through until the termination of all the lives are not often available,’ but that they provide ‘relatively reliable mortality experience at the very advanced ages.’ This paper presents the results of the mortality study of probably the only such closed group to date in the United States, the pension roll of Union Civil War veterans.