We were among them when they paused stupidly, for some reason not wishing to cross the stream.

The front ranks rolled back upon those behind, which, crowded from the rear, resisted.

The whole front of the mass wrinkled up mightily, dark humps arising in some places two or three deep.

Then the entire mass sensed the danger all at once, and with as much unanimity as they had lacked concert in their late confusion, they wheeled front and rear, and rolled off up the valley, still enveloped in a cloud of white, biting dust.
In such a chase speed and courage of one's horse are the main essentials.

My horse, luckily for me, was able to lay me alongside my game within a few hundred yards.