Patrick Power and Mary Sullivan married in Muintervara Catholic Parish on 17 September 1828.  The marriage witnesses were John Sullivan and Richard Roycroft.  Priest was Fr John P Clancy.
We do not know when or where Patrick or Mary were born as records for their likely birth era do not exist. 

Children baptised in Bantry Catholic Parish on dates on Baptismal Register:

Ellen Power, 18 Oct 1829.  Sponsors: John Power, Cathl Sullivan

John Power, 2 Oct 1831.  Sponsors: James Sullivan, Mary Sullivan

Edward Power, 9 Feb 1834.  Sponsors: Wm. Dorling, Mary Sullivan

Mary Power,

Honora Power, 17 Apr 1840.  Sponsors: Edward Fahy, Mary Sullivan

Patrick Power, 21 Aug 1842.  Sponsors: Patrick Driscoll, Ellen Hannon.  Patrick died and the next boy was given the name (not uncommon then)

Patrick Power, 20 Oct 1844.  Sponsors: Jerh Regan, Honora Murphy

By the time Patrick was aged 4 years both his parents had died.  He was taken to the United States by his older siblings, Edward and Mary arriving in Boston Port on 29 May 1849 from Bearhaven.

Note by Frank: 

In Patrick's page we read a very informed article by Charles Radosta on Patrick. It says that Patrick, aged four and a half, with his sister Mary and brother Edward sailed from Castletown arriving in Boston after five weeks at sea. Mr. Radosta's article is based on notes he made from a book "FATHER POWER" by Thomas E. Kissling and published by Belvedere Press, Baltimore, Maryland in 1931. 

Castletownbear is known locally as Castletown and also as Bearhaven with its full name being Castletown-Bearhaven. We see that the 3 ton vessel, Vixen, sailed from Bearhaven carrying 89 passengers including Edward, Mary and 4 year old Patrick arriving in Boston on 29 May 1849. Edward and Mary were far short of age 24 but not uncommon for young people to give an older age in case of being refused entry. We see on Edward's marriage on 26 Nov 1862 that he was aged 26.

This was the time of the Great Famine in Ireland

In the mid 1840’s just prior to the famine the estimated population of Ireland was around eight and a quarter million people.  Some writers believe it may have been higher and even up to, or above, 9 million.  However, whichever figure one adopts we can see from the above chart that there is a near vertical drop in the estimated population of Ireland from 1847 to 1853, which was the period of the Great Famine and a drop in population of 1.8m people.   (reference  https://bmdnotices.com/Estimated-Population-in-Ireland-19th-Century.pdf  )