The Wikipedia article Irish Rebellion of 1641 provides a fair-minded explanation of the relevant issues.

[I intend to summarise this at some time and extract the points that are particularly relevant to the Cree surname, e.g.

  • A leader of the 1641 Rebellion being Hugh Og MacMahon - possible motivation for John McMahon changing his name to Cree.
  • Brutality against Catholics in Co. Cork
  • Nature of the Rebellion, face to face with people they knew...

See also the Cromwellian Conquest of Ireland:

  • At Scarrifholis, "The [Catholic] army was now commanded by an inexperienced Catholic Bishop named Heber MacMahon."
  • Siege of Limerick etc.
  • The Cromwellian Settlement
  • Penal Laws and their link to anglicisation of surnames perceived as Catholic (eg. Creagh) to those perceived as Protestant (eg Cree)

Need also to revisit the Hstory of Clare with its specific references to Creagh families.

The following Deposition of William Allin is from the 1641 Depositons of the library of Trinity College, Dublin:

William Allin late of Newmarkett in the Barronie of doohallo [Duhallow] within the Com [County] of Corke, yeoman, a Brittish protestant, duly sworne & examined before us by vertue of &c. depose{th} & saith that on or about shrovetide the last past he lost, was robbed & forcably dispoiled of his goods & chattles to the severall values following vizt. worth 211 li [pounds]. And that Of cowes & horses to the value of one hundred & forty pounds. Of houshould stuffe to the value of tenn pouns, of haye & Corn to the value of thirty pounds, of debts amounting to the summe of six pounds six shilling. This deponent san [?since] which ere this rebellion were accounted good debts but now becom desperate by reason the debtors are impoverished such as Henry Newland, Hugh Cooke. Therfore this deponent cannot gett satisfaction from anie of them. This deponent saith that by meanes of this present rebellion hee is dispossessed of his lease of the lands of Tenforth wherin hee had a tearme of 16 yeares to come, being worth to this deponent above the landlord's rent nyne pounds per annum wherin he conceaves himselfe damnified to value of five & twenty pounds. The totall of his said losses in goods & Chattles amounts to the sume of amounts to Two hundred & eleven pounds. About midsumer last one Robert Cree of Newmarkett in the said County [of Cork], butcher, James Stackaboll of the same, sawyer, were murthered by some of the rebells. Their names he knoweth not.
William Alwine
Jurat coram nobis
5o 9bris 1642 [5 Nov 1642]
Phil: Bisse
Richard French

We also have the Deposition of Thomas and Ann Humfrey from the same collection:

Thomas Humfrey of Kilbeggan in the Countie of Westmeath, tanner, and Ann Humfry, sworne and examjned saye that since the begining of the presente Rebellion in this Kingdome Hee this deponent hath beene and is deprived, robbed or otherwise dispoyled of his meanes goodes and Chattells hereafter mentioned, vizt. fowresco{re} & tenn tannd hydes worth xlv li. [45 pounds], beasts and Cattle worth xxiiij li. [24 pounds], horses & Mares worth vj li. [6 pounds], sheepe worth xxv s. [25 shillings], 20 goates fiftie shillinges, Corne & hay in the stacks worth vj li.[6 pounds]. Howsholdstuff, provition and apparell worth x li. [10 pounds] And the Rebells in that County burned his howses and spoyled his tanpittes & dispoyled him of his farme or liveing & of corne thereon being worth x li. [10 pounds] more; And this deponent hath lost, or feareth hee shall loose by meanes of the Rebellion, in debts owi[ng] duly owing unto him the some of fforty Powndes by persons Robbed by the Rebells & soe disabled to give satisfaction Soe as his whole Losse by reason of the Rebellion amounteth to One hundreth forty fowre pownds xv s. ster[ling] <144-15s.-00> And sayth that the parties Rebells that soe deprived robbed and dispoyled him and that were, and as he thincketh yet are in Rebellion are theis that followe, vizt. Captaine Brenan of Cruagh, Brian O Neile of Laghhortonagh gen. and the Conley Mc Laghlyn, sonne to Hugh Mc Laghlyn of Newtowne: William Oge of the Garriduffe, tenant to Thomas Mc Art: William Goenin, servant to Conn McConlow whoe would not heare his complaint, Tulagh Mc Patricke of the Tuar. and Farrall of Oge of the same gen farmers. Laghlyn O Flyn of the Knocke, tenant to Rosse Geoghagan, farmer: James O Fatan & Hugh O Fatan of Balliquiggen farmers, Dermott O Skur of Brocken, Art Mc Hughes, tenant farmer, Art Cree, Michell O Cree of Ballymoyre farmers, James Coman of Kilbeggan brogmaker, Inan Mc Cormacke of the same brogmaker and Edmond O Brenan, all beare{ing} armes against his majesties subjects & is in open action

And this deponent sayth that John Adis & all his family & children mrs [fleeswore] [ ] and all the English as John Welden wen{t} to mass. And this deponent for fear of his life was constreyned 3 or 4 tymes to be att mass: And that the the towne and Abbey of Kilbegan wer burnd by Fox & other Rebells.

Thomas [mark] Humfry
marke
An Umfry [mark] her marke
Jurat 7to 7ber
1641 [7 Sep 1641]
John Sterne.
Joh Watson:
Will: Aldrich
Westmeath.
Thomas Humphrey
Jur 7o 7ber 1641 [7 Sep 1641]
Intw
Cert fact
John Sterne
John Watson
William Aldrich

One interesting feature of these two depositions is that in the first, the butcher, Robert Cree of Newmarkett, is one of those murdered by the rebels, whereas in the second, the farmers Art Cree, Michell O Cree of Ballymoyre are accused of being "yet in Rebellion."