u got smt about 8 640 hours during the era to kill ur enemy...1 Capitulation per person in 168 hours...its not so much as it look...if in start era u can recover ur army in 84-168 hours..then in the middle and late era do it is almost impossible...
In real life only strongest survive (at least in early medieval). If enemy was having way to destroy your army and rob you, nothing was preventing him to do so.
Real military game shall not be a kindergarten with regularly replaced nappies.