Its value in war was such that only after it was built did the brotherhood decide to start the siege of Dracula's castle.
从句部分倒装,built 和 did 之间无逗号,请老师分析一下句子。
这是由于only在句首引起的部分倒装。倘若不倒装便是:The brotherhood decided to start the siege of Dracula's castle only after it was built.