Playing as the Suebi. Oh i love holding Spain to myself. Started the campaign by raiding settlements arround me, and razing a path to Spain through the Western Roman Empire. Upon reaching Spain, i went through the peninsular and razed every single settlement in order to create a buffer zone.

Following this, i began to settle Spain. I secured Cordoba as my capital, then quickly moved into Lusitania. I had some threats however, and for a time was hampered by a lack of ports and finances. The faction bonus for the Suebi is incredibly useful however, as after sacking a settlement your army upkeep for that particular army is cut by 35% for 10 turns, able to stack to about 20 if you sack the same city the following turn again. Really useful to help cut down upkeep in order to develop infrastructure.

Following this, the Africa faction had grown powerful and managed to colonise the site of 'New Carthage'. I quickly moved in, took the town and therefor had hegemony over southern Spain. The Hispania faction however, took the region across the strait of Gibraltar, then stupidly declared war on me. I marched an army across, destroyed them, then made them my vassals. However, whilst continuing to develop Spain some turns later, they took the opportunity to stab me in the back. So i ended up marching south again. This time i occupied the settlement, and quickly took control over the rest of the region which had been occupied by Roman Seperatists. In this way i secured the souther approach to my wealthiest provinces.

ANyway, my question is, has anyone found a method to keep vassals loyal? Is it that i should have turned their attitude towards me positive through gifts etc?