Pennefather, John Lysaght (1800–72), general, was born in Co. Tipperary, third son of the Rev. John Pennefather, DD, treasurer (1786–9) of Cashel cathedral and rector of St John's, Newport, Co. Tipperary, and Elizabeth Pennefather (née Perceval). He entered the army as a cornet in the 7th Dragoon Guards on 14 January 1818 and was promoted to lieutenant on 20 February 1823. In November 1825 he was promoted to captain but also placed on half-pay, and did not return to active service until 8 April 1826, when he was transferred to the 22nd Foot. Subsequently promoted to major (22 March 1831) and lieutenant-colonel (18 October 1839), he was posted to India and served under Sir Charles Napier during the successful campaign against the emirs of Scinde. At the battle of Meeanee (17 February 1843), he commanded the infantry brigade, which bore the brunt of the Indian attack, and was seriously wounded. Shot through the chest, he was expected to die but recovered and was at the destruction of the fort of Imaumghur. Made a CB (4 July 1843), he also received the thanks of parliament. In 1846 he was appointed ADC to Queen Victoria (1846–54) and also later served as assistant quartermaster-general of the Cork district (1849–54).
At the outbreak of the Crimean war he was given command of the first brigade of the second division, which was under the command of Gen. Sir George de Lacy Evans (qv). He was immensely popular with his men, who referred to him as ‘Old Blood and Ounds’. Promoted to major-general on 20 June 1854, he was present at the battle of the Alma (20 September) and, when the Russians made a sortie from Sevastapol on 26 October (known as the ‘battle of Little Inkerman’), he commanded his brigade with great skill, refusing to relinquish ground to the numerically superior Russian force. During the battle of Inkerman (5 November), he commanded the entire second division, due to Evans's ill health, and played a significant part in the subsequent allied victory. Encouraging his men to contest every inch of ground, he defended the allied right flank with tenacity until French and British reinforcements could be brought up. Mentioned in Lord Raglan's dispatch, he was made colonel of the 46th Foot (19 November), and in late November was appointed to succeed Evans as commander of the second division. He returned to England, owing to ill health, in July 1855 and was made a KCB (5 July 1855).
He later served as commander of the troops at Malta (September 1855–1860) with the local rank of lieutenant-general. In February 1860 he was made colonel of the 22nd Foot and was then appointed officer commanding of Aldershot camp (1860–65). Promoted to lieutenant-general (November 1860), he was made a GCB in May 1867 and promoted to full general in May 1868. In August 1870 he was made governor of the Royal Hospital, Chelsea, an appointment he held until his death. Due to his service in the Crimean war, he was awarded several foreign decorations and orders, including the Turkish order of the Medjidie, second class, and the Sardinian order of St Maurice and St Lazarus. He was also made a grand officer of the French Légion d'honneur. He died 9 May 1872, and was buried in Brompton cemetery.
He married (1830) Margaret Carr of Mountrath, Queen's Co. (Laois); they had no children.