Finding free legal copies of classic texts like 'On War' can be tricky, but it's not impossible! Since it's an older work (published in the early 19th century), it might be in the public domain depending on your country's copyright laws. I’ve stumbled across sites like Project Gutenberg or Internet Archive, which host out-of-copyright books. They’re fantastic for digging into military theory without worrying about piracy.
That said, translations and annotated editions might still be under copyright, so you’d need to check carefully. If you’re studying Clausewitz seriously, I’d actually recommend investing in a good modern edition—the footnotes and context make a huge difference. But hey, if you just want to skim the original, those free archives are a goldmine!