my suggestion is to have a 2 part map.
you have a strategic map (probably of europe so you get ALL the ages (china and japan skipped enlightenment stage. japan went straight to industrial revolution!)
on this map you use your leaders to resemble your "armies" ( give the leader an army put the army in a bag or something)
each territory is worth X amount XP (first X is a variable)
when 2 armies enter the same area you have a battle. during any point in time units may retreat from battle (YOU HERD ME!)
retreating units must leave the table edge. have a turn limit untill reatreat (turn 3 then retreat.)
come up with a research chart (i research heavy artillery FTW!)
battles are normal brick wars however people can buy castles to fight on.

