Bro you sent 20 ships to invade an entire NATION, you also loaded these ships to the brim with missiles, meaning if they get hit like, ONCE, the entire ship is fried. You also just said "we send 5 billion soldiers" with no context, leading me to assume they're being escorted by the war vessels in transport craft, which are easily picked off once your TWENTY, TWENTY ships, are annihilated by vastly superior forces. Also just because they designed their ships a while ago doesn't mean they're outdated. Your ships are also like, very poorly designed, so there's that too.