Force structures around which western militaries were built after the Cold War, with their emphasis on comparatively small numbers of exquisite systems, will not withstand sustained combat with a peer competitor. As a consequence, there has been a growing emphasis on the employment of second tier capabilities alongside existing platforms and systems in a high-low mix spurred by the effectiveness of systems such as converted COTS UAVs in Ukraine. Such capabilities are part of a broader set of capabilities the procurement of which might be described as dissimilar rearmament. While there is considerable promise to second tier systems, enthusiasm can sometimes lead observers to elide over their vulnerabilities and the challenges associated with their employment. These challenges extend from the relative absence of formal tactical and operational concepts for the combination of mass and exquisite capabilities to the current absence of an enterprise level understanding of what would be needed to deliver capabilities at scale in terms of organisational reform, human capital and industrial policy. This Whitehall Paper discusses how dissimilar rearmament might be leveraged as an organising principle connecting R&D, industry and the armed forces across the physical, conceptual and moral components of fighting power. In doing so, it offers a means to reinforce the defence of the Euro-Atlantic area and the tactical, operational and strategic choices which will need to be made in order to realise the promise of new technology.