Which preposition to use with amain

against Occurrences 1%

But in his sleep he dreamed that Fidelis was beset by foes and cried to him for aid, whereon he would have hasted to his deliverance yet could not for that unseen hands held him fast; then strove he amain against these griping hands, and so awaked in sudden terror and lay there trembling in the dark; and in the dark he reached out cautious hand further and further and so found himself alonefor the young knight was gone.

in Occurrences 1%

But amain in their path, in a whirlwind of wrath Came young Harold, Sir Burislav's son; With a great voice he cried, while the echoes replied: "Lo, my vengeance, it cometh anon!"

Which preposition to use with  amain