Communications are so scanty that a successful manoeuvre may have incalculable results. In the Battle of the Bainsizza (middle Isonzo—August 1917), the success gained by the XXIV. Army Corps in the Vrh valley obliged the Austrians to evacuate their extremely strong positions on the left bank of the Isonzo as far as Monte Santo. In the Battle of Vittorio Veneto, the capture of Trent by the Italian I. Army (Nov. 4, 1918) enveloped and decided the fate of the Austrian units still holding out in the mountainous area between the Adige and the Brenta.
Owing to the broken nature of the terrain, strategical and tactical dispositions have to be made with great care, cannot easily be altered, and must as a rule conform to a prearranged plan. The lack of any continuous field for operations necessitates division of forces and decentralisation of command and supplies. The commander should indicate the general purpose and objective of the operation, and allow great latitude as regards the means of carrying it out ; each unit should be provided with everything required for independent action. Operations must be simple; when complicated, they often fail even if carefully organised beforehand. The slow pace of operations makes it advisable to proceed by stages, each with a separate objective. Greater length of front is imposed by the existence of tracts of impracticable country. Columns must be deeper, and therefore take longer to defile. The health and moral of the troops are of the utmost importance.
Factors Affecting Strategy.—Manoeuvre is necessarily con trolled by the terrain, larger forces being required where the mountains are narrower, lower and cut by broad valleys. Strategic surprise cannot easily be effected, because the terrain teaches the same lessons to both sides. Concentration calls for night move ments, since enemy observation is assisted by the terrain and by premature dispositions. Strategic reconnaissance is difficult. Cavalry can follow only certain fixed lines, and its reconnais sance work must be confined to limited sectors. It cannot be expected to do more than achieve contact with the heads of enemy columns. Aircraft have greater possibilities. Their field of observation is a fruitful one, because the zones occupied by enemy communications are clearly defined. Their work is ham pered, however, by atmospheric conditions, deep shadows, extensive forest areas, and the necessity of flying at great altitudes.
The disposition of the major units is a long and difficult operation. The terrain is in favour of economy of force. Great
importance attaches to the movement of the general reserve, which is usually conditioned by the road system at the junction of the valleys. If it cannot be moved freely as desired, it may be better to form local reserves. The decision is to be sought by operations wherever they may be expedient—in the bed of the valley, on the slopes, or on the heights. Operations on the heights should not, however, be an end in themselves ; every operation should be directed towards opening up the valleys, along which success can be more easily attained. As the "switching" of units is more difficult, it is advisable to adhere to the original plan.
A passive defence will always be enveloped. Movements to repulse enemy threats are hampered by the terrain.
To avoid locking up large forces in passive defence, the defender should always seek to impose frontal action on his opponent. In a defensive campaign also, the movement of the general reserve is of great importance. That it may be readily brought into use, communications will often have to be opened up or repaired, and arrangements made in advance for moving it with transport locally available.