Depending on the reason for the delay, as your final destination (MAN) was located within the European Union, AA was legally obliged to either:

a) return you to your point of origin, or
b) reroute you on another carrier to your destination

AND, if the delay was within AA's control, they're also obliged to provide

c) some sort of cash compensation.

Just now, I don't remember all the details, exceptions, etc. contained in EC reg. 261/2004, but I'm sure others (or uncle Google) will happily shed some more light on the subject.