I like the idea alot. Huge+1.
Make the initial general worse and then with skills you can get stuf like
:more units, better hp for units under the command of general, better attack dmg, speed of the general, and special stuf like general is better at commanding soldiers, other at ranged units. Maybe the rly top of the tree could be even more specialized, so directly bonus for cavalry, recruits, soldiers...
separate the tree so that we can only pick certan buffs. So that you cant get super soldiers with more hp and dmg but you either get one or the other.
this way soldiers will be specialised for blocking, killing alot of units, finishing camps and so on.