Hi Eugene Ahern
Welcome to the forum.
Your wife's Great-Grandfather, do you have a name?
The 99th were assigned to Lord Chelmsford's column, they marched to the relief of British forces under Colonel Charles Pearson besieged by the Zulu impis. At the Battle of Gingindlovu, the 99th helped defeat a Zulu impis which tried to overrun the British while laagered. Although it would not participate in the final battle at Ulundi, the 99th was honoured for its service in Anglo-Zulu War, being awarded the battle honour South Africa 1879.