Did feudalism foster wealth and well-being?

Well, the question is: for whom?

For the lords? yes, usually, except when they died in the battle.

For the peasants? Usually not. Usually what was expected of them to bring to the lords constituted a major part of their harvest and very little was left for them and their families. The poor usually were neither welathy nor well off in this system,

Will you become my friend.

Both countries had to aprove annexation.