42nd Regiment of Foot

Chronology

1756 2nd Battalion, 34th Regiment of Foot redesignated as 73rd Regiment of Foot
1763 became a Regiment of Invalids
1769 disbanded
1777 raised as the 1st Battalion 73rd (Highland) Regiment of Foot (MacLeod's Highlanders)
1778 2nd Battalion raised
1782 became the 73rd (Highland) Regiment of Foot
1809 became the 73rd Regiment of Foot
1862 became the 73rd (Perthshire) Regiment of Foot
1881 became the 2nd Battalion, Royal Highland Regiment (The Black Watch)
2006 merged with five other Scottish regiments - the Royal Scots, the King's Own Scottish Borderers, the Royal Highland Fusiliers, The Highlanders and the Argyll and Sutherland Highlanders - to form the Royal Regiment of Scotland

73rd Regiment of Foot Wikipedia
Black Watch Wikipedia
Macquarie University's webpage on the 73rd Foot (includes links to information on Seringapatam [1799] and Mangalore [1783])