Alexander Cosby Esq. (Francis, John Cosbie), of Scradbally Abbey, married Dorcas Sydney, daughter of William Sydney, Esq., of Oxford in Kent. She was second cousin co Sir Henry Sydney, Lor? Lieutenant of Ireland and a cousin of Sir Philip Sydney. This lady had been one of the maids of honor co Queen Elizabeth and through her influential connections at Court obtained grants so extensive, at that period, that the family were the territorial lords of more than a moiety of Queens County. Dorcas Sydney bore Alexander Cosby fifteen children and after his death she married Sir Thomas Zouche.
Alexander Cosby appears to have been engaged most of his time in clan warfare with the O'Moores, the hereditary princes of Leix. Camden, in his Life �of Queen Elizabeth, recites that he was once taken by Rory Oge O'Moore near Leighlin, and that he was rescued by Harpole when bound to a tree, but not before being badly wounded by Rory Oge's knife. The feud with the O'Moores endured in all it�s lawless violence until it came to an issue in 1596, when Amhcny O'Moore, the chief of the clan bearing his name, demanded a passage over Stradbally bridge and made preparations to force it, but the demand, being deemed by Cosby to be a challenge, was promptly denied. The attempt being made by the O'Moores, on the 19th of May, 1596, the Lord of Scradbally, at the head of his Kern and accompanied by his eldest son and heir, Francis Cosby, engaged in combat on the bridge, the contest being witnessed from a window in the abbey by Dorcas Sydney and her daughter-in-law Ellen. Francis Cosby had married, about a year before, Ellen, daughter of Thomas Harpole, Esq., of Thude, and had a son, William Cosby, but nine weeks old. In the conflict Alexander Cosby received a mortal wound which instantly turned the tide of battle. Francis Cosby, fearing char he would be entirely abandoned, went over the bridge in the hope of making good his retreat to the abbey, bur the instant char he cleared the battlements he was mortally wounded and fell dead into the river.
These scenes, one would suppose, would have appalled the now widowed ladies who witnessed them, yet it is recorded that Ellen Harpole, with cool presence of mind, cautioned her mother-in-law to retain her recollection how the elder Cosby fell before his son, her husband, who had thus inherited the estates for a few minutes, entitling her to her thirds of dowry. It is not stated how the ladies escaped, bur the infant, William Cosby, was carried off and preserved by his nurse. O'Moore, pursuing his victory, took possession of the abbey and, after sacking it of its valuables, consigned it to flames.
William Cosby died young. Ellen (Harpole) Cosby, the widow, married secondly, in 1615, Sir Thomas Lofrus, fourth son of Adam Loftus.
Among the fifteen children born to Alexander Cosby and his wife Dorcas Sydney, were:
1. Francis Cosby born January 1, 1571
2. Richard Cosby
3. John Cosby born in 1574 and died young.
4. Charles Cosby born September 12, 1585
5. John Cosby (the second to bear the name), born in 1589 and died young
[1] Henry Duke, Councilor - His Descendants And Connections: Comprising Partial Records of Many Allied Families; by Walter Garland Duke; Dietz Press, 1949 Virginia - Cosby Lineage page 297-298