If there was an attack on New Berlin and only 1 ASF was defending at the start of the attack, then the attack is null & void in accordance to the rules: From the updated rules section: Minimum fighters involved for a battle is 2 on each side
My point is and the rules are: If the attack started and only 1 defender was defending, then the attack by rules, is in fact null and void. Unless an over-ride in the rules was authorized.