At about eight o'clock one evening of the early summer a group of men were seated on a grass-plot overlooking a broad river. The sun was just setting through the forest fringe directly behind them. Of this group some reclined in the short grass, others lay flat on the bank's slope, while still others leaned against the carriages of two highly ornamented field-guns, whose embossed muzzles gaped silently at an eastern shore nearly two miles distant.