The Army did not begin a formal program for determining lineage and honors until the 1920s. Before that time, considerable confusion existed within the Army about the accepted procedures and methods for determining the prior history of units and their entitlement to battle honors. With the demobilization of the Army following World War I, many distinguished units were lost from the rolls. To avert such problems in the future, the Historical Section of the Army War College assumed responsibility for maintaining historical information about Army units: thus lineage work began.
Today the Force Structure and Unit History Branch continues the work begun by the Historical Section of the Army War College. The branch maintains historical information on active and inactive units in all components- Regular Army, Army Reserve, and Army National Guard, and prepares official Lineage and Honors Certificates. On the basis of research in primary and secondary material, the certificates outline the major organizational changes undergone by the unit and provide a list of the official battle honors (campaign credit and decorations) that the unit has earned. The information contained on the certificates is reformatted for publication in the Army Lineage Series
The Army Lineage Series is one of the oldest series of volumes published by the Center of Military History. Over time, the scope and concept of the series have evolved considerably, but the purpose has remained the same: to provide a compact, readily available source of information on unit organizational history. All lineage volumes have included illustrations and descriptions of unit insignia designed and manufactured by The Institute of Heraldry. Many volumes have included narrative essays of varying lengths discussing the evolution of the branch. Some branches/echelons have been covered in multiple volumes with the narrative published separately from the lineages. Most have also contained unit bibliographies. Because of the specialized terminology used on the certificates, most volumes also include a glossary.