The Anglian kingdom of Northumbria, of which York was the capital, presented in the seventh century one almost continuous series of battles and murders, massacres of the people, and desolation of the land. Ethelfrid, grandson of Ida, founder of the kingdom of Bernicia, and Eadwine, son of Ælla, founder of that of Deira, succeeded their fathers in their respective kingdoms about the same time; but the former, who had married Acca, Eadwine's sister, usurped his brother-in-law's throne and drove him into exile, who afterwards, by the assistance of Redwald, King of the East Angles, in the year 617, defeated and slew Ethelfrid in battle, and became King of Northumbria and eighth Bretwalda, or paramount monarch of Britain. He was converted to Christianity, and Penda, the pagan King of Mercia, in order to extirpate the heretical religion, invaded Northumbria, and defeated Eadwine at Hethfield, who was slain in the fight. This happened in 633, and Penda then went into East Anglia on the same mission, leaving Cadwalla, a Welsh Prince, his ally, although a Christian, as Governor of Northumbria, who made York his headquarters, and ruled the people, especially those who had embraced Christianity and were the most devoted adherents of the family of Eadwine, with the most ruthless barbarity. On the death of Ethelfrid, his sons, Eanfrid and Oswald, fled into Scotland along with Osric, son of Ælfrid, King Eadwine's uncle, where they had been converted to Christianity under the teaching of the monks of Iona, or, as Speed puts it, "had bin secured in Scotland all his (Eadwine's) reigne, and among the Red-shanks liued as banished men, where they learned the true Religion of Christ, and had receiued the lauer of Baptisme." On hearing of the death of Eadwine, they returned to Northumbria, were welcomed by the people, and assumed the crowns—Osric of Deira, and Eanfrid of Bernicia. Cadwalla was still, however, potent in Northumbria, holding York and tyrannising over the people, and they were scarcely seated on their thrones when he slew Osric in battle, and caused Eanfrid to be put to death when he came before him to sue for peace. Seeing that Christianity was almost extinct in the land, the people having reverted to the old faith, they both deemed it expedient to renounce Christianity and restore the worship of Woden, respecting which Bede says, "To this day that year (the year during which they reigned) is looked upon as unhappy and hateful to all good men; as well on account of the apostasy of the English Kings, who had renounced the faith, as of the outrageous tyranny of the British King. Hence it has been agreed by all who have written about the reigns of the Kings to abolish the memory of these perfidious Monarchs, and to assign that year to the reign of the following King, Oswald, a man beloved of God."

Oswald was an altogether different man from his brother Eanfrid, a man of genuine faith, who had imbibed the true principles of Christianity, sincere in his devotions, and prepared to undergo any suffering, even death itself, rather than apostatise from what he was fully convinced was the truth. On the death of his brother he collected around him a small army of devoted followers, and with these advanced to meet Cadwalla, relying on the justice of his cause, the bravery of his handful of men, and the assistance of God. He set up his standard, a cross, emblematic of his faith, at Denisbourne, near Hagulstad (Hexham), "and this done," says Bede, "raising his voice, he cried to his army, 'Let us all kneel and jointly beseech the true and living God Almighty, in his mercy, to defend us, from the haughty and fierce enemy, for he knows that we have undertaken a just war for the safety of our nation.' All did as he had commanded, and accordingly, advancing towards the enemy with the first dawn of day, they obtained the victory, as their faith deserved." He adds, "In that place of prayer very many miraculous cures have been performed, as a token and memorial of the King's faith, for even to this day many are wont to cut off small chips from the wood of the holy Cross, which being put into water, men or cattle drinking thereof or sprinkled with that water are immediately restored to health." He then gives some instances, one of Bothelme, a brother of the church of Hagulstad, which was afterwards built on the spot, who broke his arm by falling on the ice, causing "a most raging pain," when he was given a portion of moss from the then old cross, which he placed in his bosom, and went to bed forgetting that he had it, but "awaking in the middle of the night, he felt something cold lying by his side, and putting his hand to feel what it was, he found his arm and hand as sound as if he had never felt any such pain."

Cadwalla was utterly defeated and slain, and his vast army (vast as compared with Oswald's small band of heroes) cut to pieces and dispersed. Having thus freed his country from the one disturbing element, he applied himself to its regeneration and restoration from anarchy and desolation to peace and good order. First and foremost, his object was the re-conversion of his people from the paganism into which they had lapsed, to Christianity, and to light afresh the lamp of truth, which had been almost altogether extinguished through the vigorous zeal of Penda on behalf of his ancestral gods of the north. With this object in view he sent to Iona for missionaries, to preach and teach throughout Northumbria, and Aidan was sent at the head of a body of monks, whose headquarters were fixed on the island of Lindisfarne, as resembling that of Iona, from whence they came, hoping to make it, like the latter, a centre of evangelical light to the mainland of Northumbria. Here they lived under the rule of Columba, the founder of Iona, in monastic seclusion, when at home, which was but seldom, as they were constantly on foot, staff in hand, tramping about through forests and moors and wild places of Oswald's kingdom. The King created a bishopric, to comprehend the whole of his territories, and constituted Aidan the first Bishop, who, it is said—such was the zeal of his subaltern monkish priests—baptised 15,000 converts in seven days. Besides this, the King caused churches and monasteries to be erected in various parts of his realm, and completed the church which King Eadwine had commenced at York, the forerunner of the magnificent fane which now adorns that city and is one of the most glorious specimens of Gothic architecture in England. Nor was Oswald less active in civil and secular matters, and in promoting the welfare of his people. He governed his kingdom with great wisdom and prudence, and under his peaceful sceptre the land was rapidly recovering from the effects of Cadwalla's desolating hand. He was the fifth King of Deira, ninth of Bernicia, third of Northumbria, and the ninth Bretwalda or Supreme King of the island, "at which times the whole Iland flourished both with peace and plenty, and acknowledged their subjection vnto King Oswald. For, as Bede reporteth, all the nations of Britannie which spake foure languages, that is to say, Britaines, Red-shankes, Scots, and Englishmen, became subject vnto him. And yet being aduanced to so Royall Majesty, he was notwithstanding (which is maruellous to be reported), lowly to all; gracious to the poore, and bountifull to strangers."

It was a cold spring day; the sun shone brightly, but imparted little warmth; the trees were leafless, and the early flowers looked sickly and languid, the effect of a long continuance of north-easterly winds, which on this particular day came coursing over the ocean, and were roystering with boisterous glee and in fearful gusts round the towers of Bamborough Castle, and through the openings in the walls which served the purpose of the glazed windows of after-times. It was Easter-tide, and here King Oswald had come from York, where he had kept his Court, to celebrate this important festival of the Church in the ancestral castle of his race. The feast was laid in the banqueting-room, a tolerably large but gloomy and, to nineteenth century eyes, a wretchedly appointed apartment, with but few of the appliances of modern comfort. A fire of wood burnt on the hearth, the smoke at times passing up the wide chimney, at others driven inward by a down-current of the wind, and sent in curling wreaths along the vaulted roof. The room was lighted by means of narrow recessed openings and arrow slits, useful in times of siege, but inconveniently narrow for the admission of light, yet wide enough to afford free entrance to the chilling wind. The walls were of bare stones, and the furniture a table of rough planks running down the centre, with a smaller cross table, on a sort of dais. At the latter table were seated King Oswald, with his Queen Kineburga, daughter of Kingils, the sixth monarch and first Christian King of the West Saxons, on the one hand, and Bishop Aidan on the other. Along the other table sat some nobles and thegns, three or four of the monks of Lindisfarne, and below these the house carles and outdoor retainers of the King's household. On the cross table was placed a large silver dish filled with venison, wild boar's flesh, and other dainties; and distributed down the long table were earthen dishes containing meat of various kinds, wooden platters and knives, with drinking horns, and small loaves of barley bread; and on the table stood flagons of ale that had been brewed specially for the festival.

At the King's request the Bishop pronounced benediction on the food, with special reference to Him in whose memory the festival was celebrated, and who alone could administer the bread of life. He had scarcely finished, and the guests were beginning to handle their knives preparatory to an attack on the smoking viands, which gave forth a most appetising odour, when a sound as of a multitude of persons outside attracted their notice, and immediately after voices were heard: "In the name of Him who rose from the tomb this blessed morning, give us whereof to eat, that we starve not and die by the wayside." The King sent one of his house carles out to inquire who and what they were, who presently returned, saying that they were a band of some dozen mendicants, formerly well-to-do husbandmen, and their families, whose homes and crops had been destroyed by Cadwalla's followers, and that they were utterly destitute, deprived of the means of living, and dependent on charity for food until they could find means to replace themselves on their farms.

"Unfortunate creatures," exclaimed the King; "a fearful retribution awaits that so-called Christian prince in that world to which his crimes have sent him through our instrumentality by God's providence;" and, taking up the large silver dish, continued, "It is better that we celebrate not this festival, than that the poor of our realm die of starvation. Take this, Wilfrid, and portion out its contents among the famishing crowd, and when they have eaten, cut up the dish and distribute the fragments, that they may have the wherewithal to procure food on the morrow." Aidan, the Bishop, who was afterwards canonised, was struck with admiration at the pious and charitable act of the King, which he warmly applauded; and taking hold of his right arm, prayed that that arm and hand which had passed forth the dish might never become corrupt, but for ever remain fresh, in token and remembrance of this pious act of self-abnegation; and instead of feasting, this Easter day was spent by Oswald, his Queen, and the Bishop in fasting and prayer.

Penda, the pagan King of Mercia, was still living, and still as inveterately hostile to the new heresy as when he had made his raid on Northumbria, and trampled it out by the defeat and death of the Royal convert of Paulinus; and now, when Oswald had been eight years on the throne; had brought his kingdom, by wisdom and good government, into a condition of peace and prosperity; and had re-established Christianity on a sure and firm basis, he heard with some dismay that the heathen King was muttering threats against him, and gathering his forces together for another invasion, and a second suppression of the religion that sought the dethronement of Woden as the god of heaven. Yet although he heard these tidings with dismay, he felt assured of the Divine protection, remembering how signally he had defeated Cadwalla by fighting under the standard of the Cross, despite the disparity of numbers. He remembered, too, what miseries were inflicted on the Northumbrians by the marching of hostile bands to and fro, leaving, as they usually did, a desert behind them strewn with the corpses of men, women, and children; and he determined that, rather than allow his people to be subjected again to these sufferings, he would be beforehand with the enemy and carry the war, with its resultant ravages, into his own land. He therefore hastily assembled his fighting men, and again uplifting the standard of the Cross marched into Mercia, his troops, like those of Cromwell a thousand years afterwards, singing psalms and anthems as they passed along.

Penda had collected together a large army, and the rival hosts met at Masserfield, in the modern Shropshire. They rushed towards each other in mortal conflict, the one with shouts of "Hallelujah!" the other with cries of "Aid us, great Woden, thou mighty god of battle!" The fight was long and obstinately contested, and victory seemed to waver from one side to the other until towards evening, when an arrow struck Oswald and he fell to the ground, although not mortally wounded; but a cry arose amongst his followers that he was slain, and, thinking that their God had deserted them, they were stricken with panic, threw down their arms, and fled in every direction, hotly pursued by the Mercians, who mercilessly killed all the fugitives whom they overtook.

Although stricken down and faint from loss of blood, Oswald still lived, and witnessed with anguish of mind the cowardly and ignominious flight of his army. The Mercians came over the field, killing those of the fallen who were merely wounded; but when they came to Oswald they spared him, whom they had recognised, and brought him, with staggering steps and downcast heart, into the presence of their chief.

"Thou art he, then," said Penda, addressing him, "who darest to invade my dominions—the dominions of a descendant of Woden—thou, a worshipper of false gods!"

"It is even I," replied Oswald, in a weak voice; "I, Oswald, King of the Northumbrians, successor to the sainted Eadwine, who is now standing by the throne of the one true God, Jehovah, the God whom I worship, on whose arm I put my trust, and who, if He, in His inscrutable providence, hath delivered me up to thy cruel behests, will save my soul, that portion of me, my real self, which thou cannot touch, and bring me to dwell with Him for ever, in that heaven which thou canst never reach, unless thou repentest and abandonest thy false demon-gods, who can only conduct thee to the flames of hell."

"Blaspheming heretic," cried Penda, "I care not for the heaven thou speakest of; sufficient for me will be the Halls of Walhalla, where, amid everlasting banqueting, I will use thy skull as my drinking-cup. Still, I will give thee one chance of life. Renounce thy false god; restore the worship of Woden in Northumbria, and thou shalt be replaced on thy throne as my tributary, whilst I, as monarch of Mercia, Northumbria, and East Anglia, extending from the Thames to the Forth, and from sea to sea, shall become the Bretwalda of Britain."

"Never, O King," replied Oswald "will I prove recreant to the truth. Thou mayest rend my sceptre from my grasp; thou mayest slay my kindred and massacre my people; thou mayest torture me, and put an end to my temporal existence; but never will I renounce that faith which affords me a secure hope of everlasting blessedness, whilst thou, if thou continuest the instrument of false gods, shalt be weeping and gnashing thy teeth in the torments of the bottomless pit."

"Then," roared out Penda, "thy death be on thy own head. Soldiers, hew the blasphemer to pieces!" And immediately he was stricken by half-a-dozen swords, and fell exclaiming, "Lord Jesus, into thy hands I commend my soul."

The ferocious pagan, kicking the body with his foot as the last insult, gave directions for it to be cut into fragments, and scattered abroad to be devoured by birds of prey and the wild beasts of the forest; and his behests were at once carried into execution. And the birds and the beasts gathered together to the horrible carnival, and soon there was nothing left but the bare bones, saving one arm, which none of them would touch, and it remained entire and perfect as in life.

Some time after the battle of Masserfield the arm of the King was found, fresh and undecayed, and was conveyed to Northumbria and deposited in a magnificent shrine, where it remained uncorrupted for nine centuries, at first in the chapel of St. Peter, Bamborough Castle, and afterwards, when the Danes began to ravage the coast, in the monastery of Peterborough, whither it was removed, as Ingulphus informs us, for safety. The scattered bones were afterwards collected, by the pious care of Offryd, Oswald's niece, the daughter of Oswy, the illegitimate half-brother of Oswald, his successor on the throne of Northumbria, and slayer of Penda in battle. She had become Queen of Mercia by her marriage with Ethelred, son and successor of Penda, who, after his father's death, had embraced Christianity. She placed the relics in the monastery of Bardney, in Lincolnshire, and his "standard of gold and purple over the shrine;" but when the Danes became troublesome in Lindsey they were removed to Gloucester, "and there, in the north side of the vpper end of the quire of the cathedrall church, continueth a faire monument of him, with a chappell set betwixt two pillers in the same church." At all these places—Masserfield, afterwards called Oswestry, after the martyr; at the place of burial of the relics; and at the shrines of the uncorrupted arm—throughout those nine hundred years some most wonderful miracles were performed, which are duly recorded in the pages of Bede and other writers; even a few grains of the dust which settled on the shrine of the arm, when mixed with water and drunk, were a sovereign specific for almost any disease.

Winwick, in Lancashire, disputes with Oswestry the claim of having been the place of St. Oswald's death, as there is St. Oswald's Well there; and from an inscription in the church it appears to have been anciently called Masserfelte; moreover there is a tradition that he had a palace there, which was within his dominions, although his usual places of residence were Bamborough and occasionally York.

The village of Oswaldkirk, near Helmsley, derives its name from him, and there are several churches in Yorkshire and elsewhere dedicated to him.