Delilah of the Snows by Harold Bindloss

Two months passed almost uneventfully after the felling of the tree, for Esmond found no means of forcing the entrance to the valley. The canyon furnished the only road to it, and he found a band of determined men ready to dispute his passage each time he appeared before the tree. A company of sappers could scarcely have raised them a more efficient defense than the one they had made at the cost of an hour's labour with the axe, and Esmond reluctantly recognized that it was practically unassailable by the trifling force at his command. An attempt to carry it by assault could only result in his handful of men being swept away, and strategy proved as useless, for when the troopers floundered upstream at night through the crackling ice-cake in the slacker flow of the rapid they came to a furious rush of water, and with difficulty gained the bank again.

An attempt to crawl up to the barrier in the darkness resulted as unsuccessfully, for a man leapt up upon the log with a blazing brand almost as they left the shelter of the pines.