The blow on the head must have been struck from behind.

As he said the word, a blow was struck upon the door.

Something seemed to call them back, although no blow had been struck.

And they had a chance to strike a blow for their country.

He never seemed to get a chance to strike a blow.

But did I have any other way to strike a blow at them?

Have I ever asked you to strike a blow against, anyone?

For the English, things started to go wrong before the first blow had been struck.

Clearly such a blow must have been struck from behind.

He was still my brother, and I didn't want to be the one to strike the first blow.