Archon, possibly those cities 2 0 3 level, still have some units that leonidas da to protect the city when the game starts, and perhaps those cities even had them and no other player has attacked and for that reason your units failed, most cities that level, still have troops

for a city of level 2 or 3 leonidas send 40 javalineros defense therefore needs to send a few other swordsmen to achieve besiege ,regards