ABSTRACTThe United States (US) Office of the Under Secretary of Defense for Research and Engineering (OUSD (R&E)) launched its strategy to introduce digital engineering in 2018. This was a catalyst to modernize engineering practice across the spectrum of the US Department of Defense (DoD) activities by transforming engineering capabilities to drive agility, innovation, and efficiency into engineering practice. Since that time, the DoD, and our Military Services, government agencies, industry, academia, and international partners are implementing digital engineering. This paper provides a historical perspective of how the digital engineering concept evolved and offers insights on lessons learned.