Castelion, a cutting-edge defense technology company working to restore America's conventional deterrence capability, announced it raised $350 million in Series B financing, positioning the company to directly advance a top Pentagon modernization priority: hypersonic munitions production at scale.

The capital raise supports critical technical and manufacturing milestones: integrating Castelion's first hypersonic weapon, Blackbeard, with U.S. Army and U.S. Navy operational platforms; building its production and final-assembly facility, Project Ranger; and multi-service platform testing in 2026.

The round was led by Altimeter Capital and Lightspeed Venture Partners, with participation from Lavrock Ventures, Andreessen Horowitz, General Catalyst, First In, Space VC, Cantos, BlueYard, Avenir, Champion Hill, and Interlagos.