with might and main

Arrived before the cottage door, he drew his sword, and, taking it by the blade, pounded with might and main with the butt on the panel.

And then men saw him, "red as the rising sun from spur to plume," lift up his sword, and, kneeling, kiss the cross of it; and after, rising to his feet, set might and main with all his fellowship upon the foe, till, as a troop of lions roaring for their prey, they drove them like a scattered herd along the plains, and cut them down till they could cut no more for weariness.

In our onward course we meet nearly all these men, working with might and main, with axes, shovels, stakes and picks, hurrying as if the task were urgent.

And she, following his lead, saw that Darcy was working with might and main with some burglar's tool after the nature of a lever.

But he is building submarines and long-distance planes with all his might and main with which to bomb the convoys and to announce their location to the submarines.