Wars are rarely won by single battles. That said, it really depends what period of history you are interested in. If you want to stick to the XXth century, Anthony Beevor regularly produces very readable books on WWII or the period immediately before (mostly concerned with the European theater).
If you are interested in more ancient history, I can warmly recommend Keagan's Peloponnesian War (which mostly draws on Thucydides eponymous masterwork).
If you are interested in more ancient history, I can warmly recommend Keagan's Peloponnesian War (which mostly draws on Thucydides eponymous masterwork).