The principal, and to us the alone interesting, of his exploits seem to have lain in England, and, what is further notable, always on the anti-Svein side. English books do not mention him at all that I can find; but it is fairly credible that, as the Norse records report, in the end of Ethelred's reign, he was the ally or hired general of Ethelred, and did a great deal of sea-fighting, watching, sailing, and sieging for this miserable king and Edmund Ironside, his son. Snorro says expressly, London, the impregnable city, had to be besieged again for Ethelred's behoof (in the interval between Svein's death and young Knut's getting back from Denmark), and that our Olaf Haraldson was the great engineer and victorious captor of London on that singular occasion,--London captured for the first time. The Bridge, as usual, Snorro says, offered almost insuperable obstacles. But the engineering genius of Olaf contrived huge "platforms of wainscoting [old walls of wooden houses, in fact], bound together by withes;" these, carried steadily aloft above the ships, will (thinks Olaf) considerably secure them and us from the destructive missiles, big boulder stones, and other, mischief profusely showered down on us, till we get under the Bridge with axes and cables, and do some good upon it. Olaf's plan was tried; most of the other ships, in spite of their wainscoting and withes, recoiled on reaching the Bridge, so destructive were the boulder and other missile showers. But Olaf's ships and self got actually under the Bridge; fixed all manner of cables there; and then, with the river current in their favor, and the frightened ships rallying to help in this safer part of the enterprise, tore out the important piles and props, and fairly broke the poor Bridge, wholly or partly, down into the river, and its Danish defenders into immediate surrender. That is Snorro's account.
On a previous occasion, Olaf had been deep in a hopeful combination with Ethelred's two younger sons, Alfred and Edward, afterwards King Edward the Confessor: That they two should sally out from Normandy in strong force, unite with Olaf in ditto, and, landing on the Thames, do something effectual for themselves. But impediments, bad weather or the like, disheartened the poor Princes, and it came to nothing. Olaf was much in Normandy, what they then called Walland; a man held in honor by those Norman Dukes.
What amount of "property" he had amassed I do not know, but could prove, were it necessary, that he had acquired some tactical or even strategic faculty and real talent for war. At Lymfjord, in Jutland, but some years after this (A.D. 1027), he had a sea-battle with the great Knut himself,--ships combined with flood-gates, with roaring, artificial deluges; right well managed by King Olaf; which were within a hair's-breadth of destroying Knut, now become a King and Great; and did in effect send him instantly running. But of this more particularly by and by.
What still more surprises me is the mystery, where Olaf, in this wandering, fighting, sea-roving life, acquired his deeply religious feeling, his intense adherence to the Christian Faith. I suppose it had been in England, where many pious persons, priestly and other, were still to be met with, that Olaf had gathered these doctrines; and that in those his unfathomable dialogues with the ever-moaning Ocean, they had struck root downwards in the soul of him, and borne fruit upwards to the degree so conspicuous afterwards. It is certain he became a deeply pious man during these long Viking cruises; and directed all his strength, when strength and authority were lent him, to establishing the Christian religion in his country, and suppressing and abolishing Vikingism there; both of which objects, and their respective worth and unworth, he, must himself have long known so well.
It was well on in A.D. 1016 that Knut gained his last victory, at Ashdon, in Essex, where the earth pyramids and antique church near by still testify the thankful piety of Knut,--or, at lowest his joy at having _won_ instead of lost and perished, as he was near doing there.
And it was still this same year when the noble Edmund Ironside, after forced partition-treaty "in the Isle of Alney," got scandalously murdered, and Knut became indisputable sole King of England, and decisively settled himself to his work of governing there. In the year before either of which events, while all still hung uncertain for Knut, and even Eric Jarl of Norway had to be summoned in aid of him, in that year 1015, as one might naturally guess and as all Icelandic hints and indications lead us to date the thing, Olaf had decided to give up Vikingism in all its forms; to return to Norway, and try whether he could not assert the place and career that belonged to him there. Jarl Eric had vanished with all his war forces towards England, leaving only a boy, Hakon, as successor, and Svein, his own brother,--a quiet man, who had always avoided war. Olaf landed in Norway without obstacle; but decided to be quiet till he had himself examined and consulted friends.
