Meantime Alver, the King of the Swedes, died leaving sons Olaf, Ing, and Ingild.  One of these, Ing, dissatisfied with the honours his father bequeathed him, declared war with the Danes in order to extend his empire.  And when Harald wished to inquire of oracles how this war would end, an old man of great height, but lacking one eye, and clad also in a hairy mantle, appeared before him, and declared that he was called Odin, and was versed in the practice of warfare; and he gave him the most useful instruction how to divide up his army in the field.  Now he told him, whenever he was going to make war with his land-forces, to divide his whole army into three squadrons, each of which he was to pack into twenty ranks; the centre squadron, however, he was to extend further than the rest by the number of twenty men.  This squadron he was also to arrange in the form of the point of a cone or pyramid, and to make the wings on either side slant off obliquely from it.  He was to compose the successive ranks of each squadron in the following way:  the front should begin with two men, and the number in each succeeding rank should only increase by one; he was, in fact, to post a rank of three in the second line, four in the third, and so on behind.  And thus, when the men mustered, all the succeeding ranks were to be manned at the same rate of proportion, until the end of (the edge that made) the junction of men came down to the wings; each wing was to be drawn up in ten lines from that point.  Likewise after these squadrons he was to put the young men, equipped with lances, and behind these to set the company of aged men, who would support their comrades with what one might call a veteran valour if they faltered; next, a skilful reckoner should attach wings of slingers to stand behind the ranks of their fellows and attack the enemy from a distance with missiles.  After these he was to enroll men of any age or rank indiscriminately, without heed of their estate.  Moreover, he was to draw up the rear like the vanguard, in three separated divisions, and arranged in ranks similarly proportioned.  The back of this, joining on to the body in front would protect it by facing in the opposite direction.  But if a sea-battle happened to occur, he should withdraw a portion of his fleet, which when he began the intended engagement, was to cruise round that of the enemy, wheeling to and fro continually.  Equipped with this system of warfare, he forestalled matters in Sweden, and killed Ing and Olaf as they were making ready to fight.  Their brother Ingild sent messengers to beg a truce, on pretence of his ill-health.  Harald granted his request, that his own valour, which had learnt to spare distress, might not triumph over a man in the hour of lowliness and dejection.  When Ingild afterwards provoked Harald by wrongfully ravishing his sister, Harald vexed him with long and indecisive war, but then took him into his friendship, thinking it better to have him for ally than for enemy.