A fortress will make your empire more powerful in general and it will lessen the management and organisation that your realm needs.

A fully upgraded fortress will have the following enhancements:

• higher silver and copper capacity (200.000 pieces each)
• better exchange rates for silver and copper (silver 1:45; copper 1:3)
• shorter distance to the market from the keep (20 fields)
• higher capacity for wood, stone and ore (80.000 each)
• better exchange rates for wood, stone and ore (1:1 for each)
• shorter distance to the market (1 field)
• better base defence of the fortress wall (8.000)
• higher defence bonus (130% for each unit type)
• more available subjects (40.000)
• new offensive bonus in the barracks (+20% for each unit type)
• better resource production for wood, stone and ore (through the building levels; +45% for each resource type)
• even better resource production for wood, stone and ore (through research; +13% for each resource type)
• higher movement speed for your units (research; +5% for each unit type)
• the unit recruitment in a fully upgraded fortress is as fast as the combined speed of 5 regular castles put together.
• a fortress is able to produce significantly more offensive or defensive power per hour in conjunction with its numerous offensive and defensive bonuses

But beware: The fortress is not as powerful as the individual castles were just after it has been created. It must be upgraded in order to achieve its true potential.

Attention: All active banners will be taken down when the castles are merged into a fortress.