The 103rd Regiment of Foot (Royal Bombay Fusiliers) was a regiment raised in 1662. It transferred to the command of the Honourable East India Company in 1668 and to the command of the British Army in 1862. Under the Childers Reforms it amalgamated with the 102nd Regiment of Foot (Royal Madras Fusiliers) to form the Royal Dublin Fusiliers in 1881.
 The regiment was originally raised in England as independent companies of European soldiers to garrison Bombay in February 1662. It embarked for India later that year and was transferred to the Honourable East India Company as The Bombay Regiment in March 1668. In 1688 it was renamed The Bombay (European) Regiment – "European" indicating it was composed of white soldiers, not Indian sepoys. The regiment saw action at the Battle of Plassey in June 1757 during the Seven Years' War. It also fought at the Battle of Buxar in October 1764 during the Oude Campaign. It next saw action at the siege of Seringapatam in February 1792 during the Third Anglo-Mysore War. It fought at the Battle of Seedaseer in March 1799 and the siege of Seringapatam in April 1799 during the Fourth Anglo-Mysore War.
 The regiment fought at the Battle of Khadki in November 1817 during the Third Anglo-Maratha War. It then embarked for the Arabian Peninsula in October 1820 and saw action in operations against Omani pirates at Jalan Bani Bu Ali in March 1821.
 The regiment took part in the Conquest of Aden in 1839 and was then renumbered as the 1st Bombay (European) Regiment later in the year (on the creation of the 2nd Bombay (European) Regiment), and designated the 1st Bombay (European) Fusiliers in 1844. It took part in the siege of Multan in April 1848 and the Battle of Gujrat in February 1849 during the Second Anglo-Sikh War. It also fought at various skirmishes during the Indian Rebellion.
 After the Crown took control of the Presidency armies in the aftermath of the Mutiny, the regiment became the 1st Bombay Fusiliers in November 1859 and then the 1st Royal Bombay Fusiliers in May 1861. It was then renumbered as the 103rd Regiment of Foot (Royal Bombay Fusiliers) on transfer to the British Army in September 1862. The regiment arrived in England in February 1871.
 As part of the Cardwell Reforms of the 1870s, where single-battalion regiments were linked together to share a single depot and recruiting district in the United Kingdom, the 103rd was linked with the 102nd Regiment of Foot (Royal Madras Fusiliers), and assigned to district no. 66 at Naas Barracks in County Kildare. On 1 July 1881 the Childers Reforms came into effect and the regiment amalgamated with the 102nd Regiment of Foot (Royal Madras Fusiliers) to form the Royal Dublin Fusiliers.
 The regiment received the following battle honours granted by the Honourable East India Company:
 In 1844 the regiment was granted a number of honorary distinctions recording its past service. The awards were made by the Governor-General of India on 6 November 1844 in the following terms: "With the approval of the Right Honourable the Governor-General of India in Council, the Honourable the Governor in Council is pleased to direct, that the honorary distinctions specified below be borne upon the Colours and appointments of the 1st Bombay European Regiment, Fusiliers":
 Colonels of the Regiment were:
 Regimental titles in italics indicate they were disbanded or renumbered before 1881.