Then it brought dust with it, and Harry believed that it came from the dry soil, trod to powder by the marching feet of a great army, and the wheels of many cannon.
Comparative silence came after a while on his own side of the river.
There was no sharp sound, only a low and almost continuous murmur made by the whispering, and restless movements which so many thousands of men could not avoid.

But the sound was so steady that they heard above it the croak of frogs at the edge of the stream, and then another sound which Harry at first did not understand.
"What is it ?" he whispered to St.Clair, who lay a little higher than he.
"It's a lot of our men crossing the ford.

Raise up and you can see them walking in the water.

I take it that the general is going to put a force in the bushes and trees on the other bank to sting the Northern army good and hard before it pushes home the main attack." Standing up Harry saw men wading Bull Run in a long file, every one carrying a rifle on his shoulder.

In the hot dim night they looked like lines of Indians advancing through the water to choose an ambush.
They were crossing for half an hour, and then they melted away.