Meanwhile, with more than half a year's fighting behind them, the Italian commanders had come to certain well-defined military conclusions. The plans of General Cadorna had involved three separate campaigns--one in the Trentino, the other in the Carso, and a subsidiary campaign in the Carnic Alps to the north, along the main watershed of the mountains. A general offensive in the Trentino had been tested and found well-nigh impossible. Trentino is indeed a military paradox--a sharp salient jutting into Italy, which is strong by reason of its being a salient. This is because it is inclosed on eight sides by great walls, the batteries of the main Alpine chain. A salient is weak as a strategical situation in proportion to the possibility of crushing in its sides and threatening the lines of retreat of the forces occupying the point. Where the sides cannot be successfully attacked, it becomes a position of strength and remains a constant threat. This was the situation in the Trentino. The main Alpine chain is not impassable. It is indeed conceivable, under exceedingly favorable circumstances, that one or more of the passes on the east or west side might be taken and an advance down the valleys to the Adige turn the positions of the defenders. But ordinary foresight on the part of the defense would make this impossible. The valley of the Adige is the only avenue through the Trentino, and this avenue, which is at best only a narrow road, was heavily guarded by the strong fortress of Trent. Moreover, there could be but little result accruing to Italy if the Trentino were forced. The Adige leads only to the main chain of the Alps, and farther on, across the mountains by the easiest of Alpine highways, is the Brenner Pass. Modern defensive power is so great that its development to the point where this highway would be impregnable, except against overwhelmingly superior numbers, would be a matter of great simplicity. Along the northern frontier, in the Carnic Alps, the situation is similar. There is only one pass across these mountains, and this the Austrians could block with the same facility and certainty with which they could block the Brenner Pass.