The Robotic Technology Kernel (RTK) is a government-owned library of reusable software modules based on the first generation Robotic Operating System (“ROS 1”) that can be formed into “autonomy stacks” for integration onto defense robotic platforms. RTK has been used to demonstrate autonomous ground vehicle capabilities spanning many programs and mission scenarios over the past five years. Future use of RTK is dependent, however, on migrating it to be compatible with the 2nd generation of ROS middleware (“ROS 2”) scheduled to replace ROS 1 in May, 2025. This paper summarizes the methodologies, systems, results, and lessons learned thus far from a project to migrate RTK to ROS 2 for the purpose of informing similar ongoing or future large software-centric activities within the ROS and defense robotics communities. A key conclusion is that a well-defined set of organizational practices and technical guidance can enable a large, heterogeneous team of developers from multiple industry, non-profit, and FFRDC organizations to successfully execute a complex DoD software task.