It was, therefore, in the year 80 A.D., during his third campaign, that Agricola entered Strathearn by way of Alauna. He did not effect a permanent conquest. His operations rather resembled a reconnaisance in force. But he meant serious business. He planted forts in commanding situations, choosing so wisely, from a strategic point of view, that not one of them was ever taken or surrendered. They were placed so as to command the principal passes into the Highlands. They form a ring-fence round the territory hastily overrun by Agricola in this third campaign. Beginning in the west with Bochastle, at the Pass of Leny, near Callander, we come successively to Dalginross, at Comrie; Fendoch, at the mouth of the Sma' Glen; the camp at the junction of the Almond and the Tay; and, Ardargie, in the parish of Forgandenny, on the River May, commanding an extensive prospect of the Ochils, and along the course of the road from the Tay to the great camp at Ardoch. Here was evidently the base of operations, with accommodation, if need arose, for the entire Roman army in Scotland. Having thus viewed the land and pegged out his claim by means of forts, Agricola returned to winter quarters. In the following summer--the summer of 81 A.D., he made no forward movement. But he was meditating a great enterprise--no less an enterprise than to penetrate beyond the Tay and break the power of the Caledonians in their remote fastnesses. It behoved him to be cautious, so he constructed the chain of forts which afterwards became the Wall of Antonine--from Borrowstonness, on the Forth, to Old Kilpatrick, on the Clyde. Meantime he was laying his plans with admirable foresight. He entrusted the forts in Strathearn to the courage of their slender garrisons, and the issue proved that he could do so safely. But there was unexplored territory westward and eastward. Nobody knew what dangers might be lurking there, ready to assail him in rear the moment he left the security of his fortified place. So we find him in the summer of 82 A.D., in Argyll and Kintyre, with a small force, not fighting so much, as simply exploring, at one point feasting his Roman eyes, greedy for conquest, upon the coast of Ireland, seen dimly in the distance, and perhaps scheming in his heart and head to add it also at a fitting time to the Roman domains.