Rules for minimum defence:
To make sure, that reinforcements aren't useless, everyone should have a minimum defence of:
Villages with 700+ population: Granary level 17
Wall / Palisade level 17
Residence / Palace level 10
Villages with 600-700 population:Granary level 15
Wall / Palisade level 15
Residence / Palace level 10
Villages with 450-600 population:Granary level 12
Wall / Palisade level 12
Residence / Palisade level 7
Villages with 300-450 population:Granary level 10
Wall / Palisade level 10
Residence / Palisade level 5
Villages with 200-300 population: Granary level 5
Wall / Palisade level 5
Villages with -200 population:Do the best you can.
This will make sure, that our reinforcements won't be lost.
Thanks.