Century of Warfare is a collection of prior Operational Art of War games. Included are:

Norm Koger's The Operational Art of War Vol 1: 1939-1955 (World War 2) plus Battle Pack Volume 1
The Operational Art of War II: Modern Battles 1956-2000 (post World War 2)
The Operational Art of War II: Flashpoint Kosovo (battle pack)
An all new World War 1 database (plus some pre-made scenarios for this era).