David Garfield and Henry Harrison founded Garrison in London in 2014 to build hardware-enforced web isolation technology. The pair had worked together at national security specialist Detica and subsequently established the cyber security business unit at BAE Systems, giving them deep domain expertise in protecting the most sensitive government environments. They recognised that organisations faced an impossible trade-off: restrict web access and cripple productivity, or allow open browsing and accept the risk of web-borne threats like phishing, ransomware and drive-by downloads.

Garrison's answer was a radically different approach the company called "hardsec". Rather than relying on software virtualisation, Garrison engineered a dedicated hardware platform using ARM processor chips that turned web content into compressed, encrypted video streams, physically isolating browsing activity from the corporate network. The technology was independently verified to levels that earned the trust of highly sensitive government organisations, while remaining practical and affordable enough for commercial enterprises.

Garrison’s customers included the UK Government, the US Federal Government and major commercial institutions such as Lloyds Banking Group, spanning the banking, insurance, media, telecoms and legal sectors. Dawn led the company's $30 million Series B in 2018. In June 2024, Garrison was acquired by Everfox, the TPG-backed high-assurance cybersecurity platform, combining Garrison's hardsec browser isolation and cross-domain solutions with Everfox's existing portfolio to create a broader defence-grade security offering.