What might Key’s feelings have been if he had not seen the flag?

Answer 1

Obviously, there's no way to know for sure. He was already a patriot (or else he wouldn't have been held prisoner) so he likely would have felt pride at any sign of ongoing resistance. I doubt he would have written is poem, however.

There's something about a flag that encourages the kind of patriotic feelings that Francis Scott Key was experiencing. After what must have looked like a devastating assault, to see that the flag was still standing when the smoke cleared must have been quite a sight.