In 2018, Microsoft won a $480 million contract from the US Army to develop a mixed-reality headset to help soldiers train, rehearse and fight. The contract was slightly controversial, with a Silicon Valley consumer tech giant effectively working on developments that could make killing more efficient. However, the politics of the decision is to turn that perspective around and to describe the project as ensuring more US soldiers return from active duty safely. To get the HoloLens military project started, Microsoft engineers visited a military base in North Carolina in 2019. The engineers sought to understand "the challenging environments soldiers operate in" – which was said to be an eye-opening experience. Time and situation critical technical decisions are required by soldiers and this was observed and recorded to become 80,000 hours of feedback on headset key features. In turn this influenced Microsoft's iterative design, a key part of its user-centric approach, and updated prototypes were tested again, and so on. Testing has also spanned diverse environments in the US, as well as tropical (Puerto Rico) and arctic (Alaska) climes.