[268] This is equally true of ground that is difficult to march over; the troops must cross it. The evasion of difficult portions of terrain usually leads to disorder and a dispersion of the troops. For the advance of the 18th Infantry Brigade at Wörth, see KUNZ, _Kriegsgeschichtliche Beispiele_, 14, p. 101. (Thick underbrush in the woods on the Fuchshübel.) An attack over a plain devoid of cover “should be avoided as far as possible, or weak, widely extended detachments only should be ordered to advance over it, while the bulk of the force is launched at a point where an approach under cover is practicable. If suitable terrain is lacking to permit this, then the decisive attack must be led over the open plain.” (Par. 325 German I. D. R.). In contrast with the continuous skirmish lines of the past, which are still favored by the Austrians, the German regulations permit a gap to be left in the line where an open plain devoid of cover exists, without thereby implying that it cannot be crossed. The French regulations (par. 257), contrary to the German, contemplate that “only weak detachments be left in the open, fire swept spaces,” and that the troops intended for the fire fight be pushed forward under available cover, separate groups being thus formed.[269] [269] This should be an important hint for the opponent. The lines of approach may perhaps be sheltered with reference to a certain point, but there will always be portions of the enemy’s line from which a fire may be directed upon these avenues of approach and the troops marching thereon. “This mode of fighting in groups does away with the continuous firing lines of the past which no longer fulfill the requirements of modern battle. “The rearmost fractions of the force endeavor to avoid open spaces, or such as are swept by hostile fire, by moving, sometimes in a close order formation and again widely extended, toward the lines of cover, without regard to the direction in which the enemy may happen to be. The unit that finds the advance easiest takes the lead, and all the others, supported by the fire of their immediate neighbors, endeavor to follow it. “Depending upon the character of the terrain and available cover, the forces deployed for the fire fight will, therefore, advance in a rather dense formation in the areas favorable for such a procedure, while weak forces only will be found on open and fire swept ground. The advance is regulated by designating the objective of the attack and by stipulating the necessity of mutual coöperation.”