Is Bitcoin useful in war or disaster scenarios without electricity?

In the event of a large-scale war, EMP attack, or severe natural disaster (like hurricanes or flooding) that knocks out electricity and internet access, how would Bitcoin function as a currency? Could it still be a viable option, or would people revert to using traditional currencies or barter systems in such situations? How could Bitcoin's decentralized nature help or hinder its usability in these scenarios? Interested to hear all your thoughts!