The Viking Invasions:
According to the sagas, during this period the Vikings were oppressive and onerous foreign invaders in Ireland, e.g. they reputedly cut off the noses of those that did not pay them yearly taxes, displaced native landowners and forcibly took the best land, forcibly removed young people to other countries, billeted Viking warriors in private homes, etc.. Many written sources describe how domineering and how miserably they treated the native Irish in the areas they controlled (see e.g. The War of the Gaedhil with the Gaill, J. Todd, 1867; Bugge 1905). On the positive side, they founded many towns in Ireland and engaged in commerce (as well as piracy). Some contemporary historians argue for a revision of this view of the Vikings and argue that they were more peaceable and more assimilated into the culture (Maire Ni Mhaonaigh 1998; O Corrain 1998).
The chaos of Ireland in the early tenth century (the period just before Ceallachan was elected king in 944 AD) has been described by historians Peter and Fiona Somerset Fry as follows:
"Early in the tenth century there was a renewal of large-scale Viking raids on Ireland. This time the raiders came not from Scandanavia but from Scotland and northern England, made up of warriors from families long established in those parts. Many areas were attacked, and the worst affected area appears to have been Munster, which was penetrated deeply in several sectors" (Frey and Frey, 1988, A History of Ireland, Routledge: London and New York, p. 52).
This makes clearer what was meant when an Irish poet described Ceallachan as
"Ceallachan chosnas a chro."
"Ceallachan who defends his home" (Bugge 1905).
Early events during Ceallachan's reign
"Ceallachan of Munster . . . after his accession, had begun to rebuild Eoghanacht supremacy in the kingdom, taking the Danish strongholds in Cork and Waterford. Following the usual procedure, the towns had been evacuated, but not reduced, after their capitulation; and while Ceallachan concentrated on his scores with the Ui Neill, he allowed the Danes slowly to return and restore.. . . The Ardri ["High King" or monarch], Donnchadh, viewed developments in silent fury for, as the annalists recount [The Annals of the Four Masters] he 'displayed no great talents or patriotism, and envied the exploits of Ceallachan, which he ought to have imitated . . .'" (Newman 1983:61).
A Cleric and Warrior from the Cross of the Scriptures, Clonmacnoise (McClintock 1950: Fig.3; Photo by T. H. Mason & Sons, Dublin).
What it meant to be an Eoghanact and the King of Munster.
O Corrain has stated that: "According to the classical law tracts, there were three distinct grades of king: ri or ri tuaithe, the king of the local tuath or petty tribal kingdom; ruiri or great king who, in addition to being king of his own tuath, was the personal overlord of a number of other tribal kings; and lastly, ri ruirech or 'king of overkings', who is identified with the king of a province. No higher grade of king, 'high king' or king of Ireland is known to the classical law texts" (O Corrain 1972:28). Ceallachan was a ri ruirech or king of overkings i.e. the king of the province of Munster. Munster was the largest, richest, and most beautiful province of Ireland.
The kingship of Munster was a "well-developed institution.. . . An early law tract states baldly that 'supreme among kings is the king of Munster' and the dictum bespeaks a self-confidence which is borne out by the annals. Another law text refers to the special position of the provincial king in terms of his rechtgae rig 'special royal ordinance', 'as in the case of the rechtgae of the king of Cashel'" (D. O Croinin, 1995, Early Medieval Ireland 400-1200, Longman: London and New York. pp.58-59).
Ceallachan identified himself (as did his followers) as an Eoghanacht of Munster. In the second century Oilill Olum was said to have controlled all of southern Ireland. He divided it between his sons Cormac Cas and Eoghan Mor. The descendants of Oilill Olum are the Eoghanacta (Newman 1983:49). The Dal Cas of Thomond (northern Munster) trace their lineage through Cormac Cas and the Eoghanact trace their lineage through Eoghan Mor. Ceallachan claimed to be a direct descendant in this royal line and that is part of the reason why he was able to successfully become king. He was elected by 17 tribes as their leader. He probably was perceived by those that made him king to be able to do something to restore Munster and the Eoghanacts.
As the Eoghanacht king, Ceallachan would have to militarily drive the Danes and Norwegians out of Cashel, Cork, and Waterford, keep the Ui Neill's of Ulster out of Munster, and keep the Dalcassians of Munster who were allies, but also competitors for the kingship of Munster, which alternated, from usurping him.
The monastery at Clonmacnoise was in Ui Neill controlled territory and was generally allied with the Ui Neill's of Ulster (and was therefore no friend of an Eoghanacht Munster). According to Bart Jaski, "The influence of the Vikings on political developments in Ireland from c.850 to 980 was considerable, and they contributed significantly to the decline of the Uí Néill as the paramount dynasty. On several occasions they served as mercenaries or allies of Irish kings who resisted the power of the king of Tara" (Jaski, Peritia 9; 1995:310-53). According to the Chronicum Scotorum, Danes and Ceallachan's men both plundered Clonmacnoise. It was also plundered by other churchmen and other Irishmen over the centuries. The annals report a couple of hundred instances of the plundering of monasteries over time, often by Irish forces. Different monasteries even raised armies and went to war with each other and other political leaders. O Corrain states that after 849 AD "the Vikings had become familiar with the country; they had founded small but fairly permanent settlements and had become a factor in the country's politics, and they were accepted as such. Likewise the Irish had grown familiar with them, and from this point Norse-Irish alliances, especially in the incessant dynastic squabbles and in the struggle for paramountcy amongst the Irish kings, became commonplace. Nor were such activities looked upon with reproach" (O Corrain 1972:92-93). O Corrain points out that Viking cities in Ireland sometimes attacked each other (e.g. Vikings from Dublin attacked Viking Limerick in 924 AD) and sometimes one Viking city allied with the Irish to drive out Vikings from another city (e.g. Viking Limerick allied with the Irish in Munster in 926 AD to repel an incursion from the Vikings of Waterford). A couple of modern ethnocentric historians have tried to adopt a moralistic tone as a result of an entry in the annals that Ceallachan "partaked with Danes" however temporary alliances of that nature were commonplace during that century.
The High Kingship of Ireland was not hereditary and shifted from province to province over time so the fact that an Ui Neill happened to be High King at the time did not mean it would stay there. The Kings of Munster had been High Kings both before and after this period. According to the Frys, "There was practically no cooperation, no understanding of alliance, between the four main kingdoms (Ulster, Connacht, Leinster, Munster), or between the many subkingdoms nominally owing allegiance to one or other of the four. Indeed, few Irishmen grasped the concept of national unity. The high kingship, which in theory carried the right to call out a national army in time of danger, was seldom recognized in any one person by everyone else. The role was not an hereditary one, even though the Ui Neills who, from Tara, ruled much of the north and some of the east, had some claim and did from time to time assert it" (Fry and Fry 1988:53).
Ceallachan basically accomplished all of these military and political goals in about ten years and also demonstrated the personal qualities people looked for in a tenth century king. For this he was apparently loved by his followers and respected and feared by his enemies.
Hindsight and Historical Perspectives
Later historians do not necessarily view individuals from the perspective of their own time. Some historians who look backwards in time with a nationalist and pro-monarchist perspective see provincial kings asserting and restoring their traditional rights as impediments to the gradual historical progress of nationalism (and thus those pesky Scots should never have opposed rule from London). Historians often disagree with each other on major points.
Some historians like Peter and Fiona Somerset Fry (1988:53) who, in hindsight, see the major threat to Ireland in the tenth century to have been the Viking foreigners, somehow claim he did not do enough to drive them out and restore Eoghanacht power (a rather easy thing to say from an armchair a thousand years later. If they actually were standing in the front lines facing a foreign enemy with superior armor I suspect they might have a slightly different perspective of Ceallachan's accomplishments. The Freys do acknowledge that he had to contend not only with the Vikings but with threats from the Ui Neill's who temporarily, at least, made him a captive as described in the Circuit of Ireland).
You should keep in mind that although he and his followers won their battles, Ceallachan's enemies, including monks whose monasteries had been sacked by Ceallachan, wrote some of the history and the poems such as in the various annals and The Circuit of Ireland.
This would be analogous to reading a biographical description of William Wallace (the thirteenth century historical figure portrayed in the movie "Braveheart") written by his political enemy, King Edward I.
In the ever changing period of struggles, invasions, and quickly shifting alliances between 300 AD and 1100 AD it was not clear which, if any, area might end up in control of Ireland, and if that control would only be temporary. Historically, the King of Munster did not recognize any higher legal authority. Donnchadh, the Ui Neill High King, (not to be confused with Donnchadh of Caem, Ceallachan's friend and ally) had approved the Viking plot to kill Ceallachan and they were mortal enemies.
There is some indication that Ceallachan considered himself a high king (with a small "h") as opposed to what a historian might call a "petty" king. Munster was a free territory and Ceallaghan was presumably responsible for maintaining that free status.
Ireland had areas of free territories and areas of subjection. At the time that Muircheartach of the Leather Cloaks was traveling clockwise ('keeping his left hand to the sea') around Ireland taking hostages (like Ceallaghan of Cashell), to consolidate his power as heir to the throne, he was allied with the Ui Neill (Ui Niall), Donnchadh, the Ardri, "High King," or monarch.
In earlier years, however, this same Muircheartach had feuded with Donnchadh (the High King) and they had been enemies. The two laid aside their differences just before a battle.
Muircheartach, who was the heir to the throne of Ireland, undertook an unexpected winter expedition with 1000 men around Ireland to consolidate power. The long standing practice of taking hostages was to ensure political loyalty (or at least temporary control) and could avoid battles.
A. J. Goedheer in Irish and Norse Traditions about the Battle of Clontarf (Haarlem:Tjenk & Zoon) described this episode as follows:
"A remarkable feat was accomplished by Niall's son Muirchertach of the Leather Cloaks, king of Aileech, who made a circuit of all Ireland with a thousand men in 941 and brought back the hostages of the kingdoms, except those of the Dal Cais in co.Clare. The hostages were handed over to the reigning high-king Donnchadh. This campaign was held in winter and the warriors protected themselves against the cold by the leather cloaks from which the king received his surname. Their arrival must have made a deep impression, for the circuit was achieved almost without a blow being struck. A campaign round the whole country, and in winter too, was an event without precedent. High-kings usually preferred to interfere as little as possible with the neighboring kingdoms, especially with Munster, which for a long time had held an isolated position" (Goedheer 1938:113-114).
Daily Life in Ireland during the 10th Century
This is a very large subject. For further reading on this topic you might want to consult Donnchadh O Corrain's Ireland before the Normans (1972) where he generally describes politics and society in Ireland during the 350 years between the first Viking raids and the Norman invasion. Chapter 2 describes the structure of Irish society and of the economy during this period.