Her uncle Óengus Gaíbúaibthech comes to rescue her, but Cellach refuses to release her.

* Second, on a visit to Midir ( escorted by Lug, the Dagdae and Ogmae ), Fúamnach announced that she would drive Étaín away from him and employed a spell which she had learnt from her fosterfather: she conjured up a mighty wind which blew Étaín through the air for the duration of seven years, after which she came to Óengus ( Mac Óc ) in the Brug.

Something of Óengus ' view on secular politics appears to come through in his prologue to the Félire.

He, along with Bóand, helped Óengus search for his love.

In 744 the Picts acted alone, and in 750 Óengus may have cooperated with Eadberht of Northumbria in a campaign in which Talorgan, brother of Óengus, was killed in a heavy Pictish defeat at the hands of Teudebur of Alt Clut, perhaps at Mugdock, near Milngavie.

Æthelbald, who might have been allied with Óengus, the king of the Picts, took advantage of Eadberht's absence from Northumbria to ravage his lands, and perhaps burn York.

Eventually it lands on the clothes of Óengus, who recognises it as Étaín, but he is at war with Midir and cannot return her to him.

The legend surrounding Scotland's association with the Saint Andrew's Cross was related by Walter Bower and George Buchanan, who claimed that the flag originated in a 9th century battle, where Óengus II led a combined force of Picts and Scots to victory over the Angles, led by Æthelstan.

The Flag of Scotland shows the Saltire of Saint Andrew and is traditionally associated with Óengus mac Fergusa.

Previously thought to have been of Dál Riatan origin and descended from Fergus mac Echdach, their family is now assumed to have been that of the first king Óengus mac Fergusa, perhaps originating in Circinn ( presumed to correspond with the modern Mearns ), a Pictish family with ties to the Eóganachta of Munster in Ireland.

Óengus, along with his brother, son Eogán, and nephew Domnall, is included in the Duan Albanach, a praise poem from the reign of Máel Coluim ( III ) mac Donnchada listing Máel Coluim's predecessors as kings of Scots, of Alba and of Dál Riata from Fergus Mór and his brothers onwards.

The later St Andrews tradition recounting the supposed arrival of Saint Regulus ( or Saint Rule ) at St Andrews, with relics of St Andrew, has him met at Forteviot by three sons of Óengus: Eogán, Nechtan and Finguine.

Dúngal later returned to Scotland, and was captured in 736, along with his brother Feredach, by Óengus.

According to legend, Achaius, King of Scots ( possibly coming to the aid of Óengus mac Fergusa, King of the Picts ), while engaged in battle at Athelstaneford with the Saxon King Æthelstan of East Anglia, saw in the heavens the cross of St Andrew.

Later scribes added a prose preface, including material on Óengus, and accompanied the text with abundant glosses and scholia.

These pagan seats of power are contrasted with the great ecclesiastical centres of Ireland which were flourishing in Óengus ' own time, such as Armagh and Clonmacnoise.

" Not satisfied with his hermitage, which was only a mile from Clonenagh, and, therefore, liable to be disturbed by students or wayfarers, Óengus removed to a more solitary abode eight miles distant.

Mongfind also occurs as the name of the Pictish princess wedded to Conall Corc, ancestress of the Eóganacht Locha Léin of Iarmuman and of a line of powerful Pictish kings, e. g. Óengus I of the Picts, but it appears this can be dismissed as a case of coincidental influences on the story associating Crimthann mac Fidaig with the Pictish king and father, called Feredach.

Óengus is said to have fathered Fíacha on his own daughter when drunk, and to have put him in a boat, wrapped in a purple robe with a golden fringe and accompanied by treasure, and set him out to sea – hence the epithet fer mara, " man of the sea ".

It may be that Óengus was involved in wars in Ireland, perhaps fighting with Áed Allán, or against him as an ally of Cathal mac Finguine.

A defeat here for Eadberht and Óengus by Æthelbald's Mercians would correspond with the claim in the Saint Andrews foundation legends that a king named Óengus son of Fergus founded the church there as a thanksgiving to Saint Andrew for saving him after a defeat in Mercia.

Later generations may have conflated this king Óengus with the 9th century king of the same name.

Óengus, like his successors and possible kinsmen Caustantín and Eógan, is recorded prominently in the Liber Vitae Ecclesiae Dunelmensis, a list of some 3000 benefactors for whom prayers were said in religious institutions connected with Durham.

The following 9th century Irish praise poem from the Book of Leinster is associated with Óengus:

This sequestered place, two miles southeast of the present town of Maryborough, was called after him " the Desert of Óengus ", or " Dysert-Enos ".

His earliest biographer in the ninth century relates the wonderful austerities practiced by St. Óengus in his " desert ", and though he sought to be far from the haunts of men, his fame attracted a stream of visitors.

Énna Aignech (" spirited, swift ", an epithet usually applied to horses ), son of Óengus Tuirmech Temrach, was, according to medieval Irish legend and historical tradition, a High King of Ireland.

Irish genealogies make Óengus a member of the Eóganachta of Munster, as a descendant of Coirpre Cruthnechán or " Cairbre the little Pict ", a mythological emanation or double of Coirpre Luachra mac Cuirc, legendary son of Conall Corc, and ancestor of the Eóganacht Locha Léin, rulers of the kingdom of Iarmuman.

The Irish annals report the death of " Tuathalán, abbot of Cinrigh Móna ", in 747, making it certain that St Andrews had been founded before that date, probably by Óengus or by Nechtan son of Der-Ilei.

The sophisticated kingdom that had been built fell apart, as did the Pictish leadership, which had been stable for more than a hundred years since the time of Óengus mac Fergusa ( The accession of Cináed mac Ailpín as king of both Picts and Scots can be attributed to the aftermath of this event ).

Having interpreted the cloud phenomenon as representing the crux decussata upon which Saint Andrew was crucified, Óengus honoured his pre-battle pledge and duly appointed Saint Andrew as the Patron Saint of Scotland.

The independent existence of the kingdom of the Cenél Loairn, and that of Dál Riata, probably ended in 736, after which time it formed part of the kingdom of the Picts, ruled by Óengus mac Fergusa.

There are reasons for believing that Óengus was ordained to the office of bishop, a denomination which is first assigned to him in a list of saints inserted into the Martyrology of Tallaght ( see below ).

The literary effort most commonly attributed to Óengus is the Old Irish work known as Félire Óengusso (" Martyrology of Óengus "), which is the earliest metrical martyrology — a register of saints and their feast days — to have been written in the vernacular.

Óengus and the Picts appear occasionally in Welsh sources, such as the Annales Cambriae, and more frequently in Northumbrian sources, of which the Continuation of Bede's chronicle and the Historia Regum Anglorum attributed to Symeon of Durham are the most important.

Alpín was defeated twice by Óengus, after which Nechtan was restored to power.

On 12 August 729 Óengus defeated and killed Drest in battle at Druimm Derg Blathuug, a place which has not been identified.

The 750 battle between the Britons and the Picts is reported at a place named Mocetauc ( perhaps Mugdock, near Milngavie ) in which Talorgan the brother of Óengus was killed.

The amount of information which has survived about Óengus compared with other Pictish kings, the nature and geographical range of his activities and the length of his reign combine to make King Óengus one of the most significant rulers of the insular Dark Ages.

Kingarth ( Cenn Garadh ) and Eigg ( Eic ) were described as " in Galloway " ( Gallgaidelaib ) by the Martyrology of Óengus, in contrast to Whithorn — part of modern Galloway — which was named as lying within another kingdom, The Rhinns ( Na Renna ).

It has been suggested that Óengus was actively involved in the compilation if not the composition of the augmented Martyrology of Tallaght.

This rests largely on a confused passage in Symeon of Durham's Historia Regum Anglorum, and it has more recently been suggested that the interpretation offered by Frank Stenton — that it is based on a textual error and that Óengus and Æthelbald were not associated in any sort of joint overlordship — is the correct one.

It has been suggested that the St Andrews Sarcophagus was commissioned by Óengus to hold Nechtan's remains, although it is more generally supposed that the sarcophagus was for Óengus himself.