Public-sector entities, like many commercial ones, are increasingly undertaking large transformation programs to streamline and improve their core operations. Nowhere is this task more challenging than in the US Department of Defense (DoD), which is committed to transforming its business practices to support faster and more agile operations. This multiyear mission will touch all aspects of the DoD, which has annual net operating costs exceeding $620 billion—including more than $30 billion for technology—2.9 million people, and a supply chain involving 5.2 million items.

In 2005, the DoD established the Business Transformation Agency (BTA) to help guide transformation efforts throughout the department. The BTA’s responsibilities include deploying enterprise IT systems, publishing the Business Enterprise Architecture, and helping to carry out investment decisions. The agency, for example, oversees programs that manage pay and travel for the armed services, makes proposals to organizations such as the army and the navy (called “components” inside the Pentagon) about how they can transform themselves most effectively, and encourages standardization throughout the department.

Few people have as good a position to reflect upon the DoD’s transformation as David Fisher, the BTA’s first official director. Fisher joined the DoD from Silicon Valley, where as a consultant he helped...