I've never really understand the difference between these 3 structures :
ものすごいスピードで攻撃したのですが...
ものすごいスピードでの攻撃をしたのですが...
ものすごいスピードでの攻撃だったのですが...
I wouldn't be surprised if the first 2 were totaly interchangeable, but what about the third? Does it have a particular nuance or is it virtually the same as the others?