# Castelion Defense startup building mass-produced hypersonic weapons — the first U.S. company designing hypersonic munitions for industrial-rate production rather than artisanal one-offs. Founded by former [[SpaceX]] executives who are applying rocket manufacturing principles to weapons production. Backed by [[Andreessen Horowitz]]'s [[American Dynamism]] fund. ## Key Facts - **Valuation:** $2.8B (Series B, December 2025). - **Total raised:** $464M+ across seed, Series A ($100M, Jan 2025), and Series B ($350M, Dec 2025). - **Series B** led by [[Altimeter Capital]] and Lightspeed Venture Partners, with participation from a16z, General Catalyst, Lavrock Ventures, BlueYard, First In, Space VC, Cantos, Avenir, Champion Hill, Interlagos. - **Series A** included $70M equity + $30M venture debt from Silicon Valley Bank. - a16z participated from seed stage through Series B. ## Products - **Blackbeard** — First U.S. hypersonic system engineered from inception for industrial-rate output and commercial unit cost. Not a prototype — designed for mass production from day one. - Conducted **20+ development flight tests in 2025**, validating weapon-critical subsystems: solid rocket motors, control actuation, flight computers, seekers, thermal protection, and mission software. ## Why It Matters Hypersonics are the Pentagon's #1 capability gap. China and [[Russia]] have operational hypersonic weapons; the U.S. has struggled with over-budget programs at legacy primes. Castelion's thesis mirrors [[Anduril]]'s and [[Hadrian]]'s: apply Silicon Valley speed and manufacturing principles to defense production. The SpaceX pedigree matters — SpaceX proved that a startup could out-manufacture legacy aerospace on rockets. Castelion is betting the same approach works for missiles. ## a16z Connection Castelion is a core [[American Dynamism]] portfolio company. a16z invested at the seed stage when Castelion was still in stealth, and has participated in every subsequent round. The company exemplifies [[Katherine Boyle]]'s thesis that the best defense companies will look like manufacturing startups, not traditional defense contractors. ## Funding - [[Castelion $1B Series C]] — August 19, 2026; **$1.05B at a $13B post-money valuation**, co-led by [[Andreessen Horowitz]], [[Carlyle]] and [[JPMorgan Chase]]. The round followed **more than $500M in U.S. military contracts**, not the other way round. ## See Also - [[Andreessen Horowitz]] - [[American Dynamism]] - [[Hermeus]] - [[Hadrian]] - [[Anduril]] - [[Defense Tech as Asset Class]]