The placename Cameirge is poorly attested in the sources. It appears only in the context of a 1241 battle of which the Annals of Ulster state:
Cath Caimeirghi tuc Brian O Neill 7 Mael Sechlainn O Domnaill rí Ceniuil Conaill do Domnall Mag Lachlainn do righ Tire hEogain gurmarbadh Domnall Mág Loclainn ann 7 deichnebur da derbfhine fein ime 7 taisigh Ceniuil Eogain uile 7 daine maithi imdhai aili fós 7 righi do gabail do Brian O Neill da eis
'The battle of Cameirge was given by Brian O Neill and Maelsechlainn O Donnell king of Cenél Conaill to Domhnall MacLochlainn the king of Tír nEoghain so that Domhnall MacLochlainn was killed with ten of his derbfhine around him and all the chiefs of Cenél nEoghain and many other good people likewise and the kingship was taken by Brian O Neill'
Similar entries are found in other annalistic strands but none of these contain any additional material that might allow us to fix the battle in the landscape. Fortunately the battle is alluded to in a contemporary praise poem composed by Giollabrighde MacConmidhe for his patron O Donnell . Though the battle is not expressly mentioned, the central portion of the poem clearly concerns itself with the build up to the event described in the Annals of Ulster:
Tar Ard Sratha tar Sliabh Truim
Is cosgrach cuairt I Dhomhnuill
An cuiléan ó Chlár Maighne
Lámh re muinéal Modhairne
A aghaidh suas ar Sliabh Cairn
A chúl amach re Modhairn
Annsa ród ar chuir an cath
Amuigh ar fód O bhFiachrach
An dara cuing an chatha
Ar Brian Eamhna ardMhacha
Sa leathchuing re taoibh sa troid
Ar Maoil Eachluinn ó Fhánoid
'Over Ard Sratha
Over Sliabh Truim
Devastating was the foray of O Donnell
The whelp of Clár Maighne was hard by the bend in the Modharn
With his face towards Sliabh Cairn
And his back to the Modharn
He was on the road where he joined battle
Upon the turf of the Uí Fhiachrach
The second half of the yoke of battle
Was upon Brian of noble Eamhain of noble Macha
And the other half beside him in the battle
Was upon Maelsechlainn of Fánaid'
To anyone familiar with the conceits of such poetry the personalities alluded to are clearly Maelsechlainn O Donnell (=O Donnell, Maelsechlainn of Fánaid) and Brian O Neill (=The whelp of Clár Maighne, Brian of noble Eamhain of noble Macha) and the placename literature allows us to place the build up in the north of modern County Tyrone (Ard Sratha=Ardstraw, Sliabh Truim=Bessy Bell mountain, Modharn=Mourne river, Sliabh Cairn=Mullaghcarn mountain, Uí Fhiachrach=northern County Tyrone). Plotting these locations on a map it becomes clear that O Donnell is moving along an axis extending from Ardstraw through Newtownstewart (where he meets up with O Neill) towards Gortin and that Cameirge most probably lies upon an extension of that axis.
Several locations have previously been suggested but none of the identifications are particularly strong. The various locations, their basis of identification and some comments follow:
Near Maghera, County Derry 
Basis: a tradition that Slaghtneill, near Swatragh, County Derry was the site of a battle between MacLochlainn and O Neill in which a Niall MacLochlainn was killed .
No Niall MacLochlainn is noted in the annalistic or poetic account of the battle and so the tradition is not particularly persuasive as being traditional of the battle the annalists tell us was fought at Cameirge. While Slaghtneill does lie upon a reasonable political boundary between the combatants it can not straightforwardly be construed as falling within the general onward direction taken by O Donnell and O Neill to the battle.
On borders of Tír Conaill and Tír nEoghain 
Basis: association with the political boundary of the combatants .
Ardstraw lay within Tír nEoghain  but in the poetic account Ardstraw has already been passed by O Donnell on his way to meet up with O Neill so it would seem that the area of Tír nEoghain immediately east of Ardstraw to the south of the Sperrin mountains was already in the hands of O Neill and so denied to MacLochlainn.
Camderry, near Dromore, County Tyrone 
Basis: similar name.
Camderry can not reasonably be construed as falling within the general onward direction taken by O Donnell and O Neill to the battle and is far removed from any reasonable political boundary between the combatants. Also, the poetic account indicates that the area immediately east of Ardstraw to the south of the Sperrin mountains was in the hands of O Neill so it is difficult to envisage how MacLochlainn based to the north of the Sperrin mountains was to arrive there.
Cummery, near Omagh, County Tyrone 
Basis: association with a diocesan boundary that could reflect a political boundary between the combatants, similar name, lies within the general onward direction taken by O Donnell and O Neill to the battle.
Cummery is the strongest of the previous identifications but we have already seen that the poetic account indicates that the area immediately east of Ardstraw to the south of the Sperrin mountains was in the hands of O Neill so it is difficult to envisage how MacLochlainn based to the north of the Sperrin mountains was to arrive there.
Camberry, near Drumquin, County Tyrone 
Basis: similar name.
Camberry can not reasonably be construed as falling within the general onward direction taken by O Donnell and O Neill to the battle, is far removed from any reasonable political boundary between the combatants and we have already seen that the poetic account indicates that the area immediately east of Ardstraw to the south of the Sperrin mountains was in the hands of O Neill so it is difficult to envisage how MacLochlainn based to the north of the Sperrin mountains was to arrive there.
A New Identification
In the nineteenth century John O Donovan noted a tradition of a battle between MacLochlainn and O Neill at a ridge called Eiscir Mhic Lachluinn ('MacLochlainn's Esker') in Altihaskey, Ballinascreen, County Derry at which the MacLochlainn chief was killed . An esker is a distinctive landscape feature, a long steep-sided and sinuous ridge of sand and gravel deposited by a sub-glacial stream. An examination of map and landscape reveals that the only esker in the vicinity of Altihaskey lies among a group of glacial features described as Davagh Eskers [sic] a few yards over the county boundary in Davagh, County Tyrone. Fortunately the Ordnance Survey Memoirs note that the county boundary in this area was not fixed until quite late  and so the esker in Davagh can safely be identified as the esker of the tradition. Having fixed Eiscir Mhic Lachluinn in the landscape we can proceed to marshal several pieces of evidence in support of its identification with Cameirge:
The modern placename contains the surname of one of the parties to the battle and so can be seen to supercede the placename existing at the time the battle took place whereas the existence of three seperate locations having modern placename similar to Cameirge serve by their mutual denial to dilute the value of such bare similarity as evidence. Under this more sophisticated analysis bare similarity of placename is deprecated as superficial and so the new identification can be seen to possess an evidential quality far in excess of those previously made. It cumulates the elements of tradition, topography, direction and boundary association at a single point in the landscape accessible by all three parties to the battle and on that basis is to be preferred, leaving Eiscir Mhic Lachluinn firmly identified as the battle-site once known to the annalists as Cameirge.