For the World War II formation see 12th Indian Infantry Division
The 12th Indian Division was formed in March 1915 from units of the British Indian Army

British Indian Army

The British Indian Army, officially simply the Indian Army, was the principal army of the British Raj in India before the partition of India in 1947...

. It formed part of the Tigris Corps, for service during the Mesopotamia Campaign of World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. The Division arrived in Mesopotamia in April 1915 and remained there until it was broken up in March 1916.
The Division's brigades remained in Mesopotamia as independent formations until forming part of the 15th Indian Division in May 1916.
During its short existence it fought in a number of actions including the Battle of Shaiba

Battle of Shaiba

The Battle of Shaiba, 12–14 April 1915 was between British forces and Ottoman forces that were trying to retake the city of Basra from the British.-Background:...

 between April 12–14, 1915, the Battle of Khafajiya between May 14–16, 1915, the Battle of Nasiriya between July 5, 13-14, 24 1915, where 400 British and Indian soldiers were killed in the battle and up to 2,000 Turkish Soldiers. The Occupation of Nasiriya and the affair at Butanuja, January 14, 1916.

12th Indian Brigade

Commanding Officer, Brigadier K E Lean

• 2ns Btn Queen's Own Royal West Kent Regiment
• 4th Prince Albert Victor's Rajputs
  4th Prince Albert Victor's Rajputs
  The 4th Prince Albert Victor's Rajputs was an infantry battalion of the British Indian Army. They could trace their origins to 1798, when they were the 2nd Battalion, 16th Bengal Native Infantry. Over the years they became known by a number of different titles...
  
  
• 44th Merwara Infantry
  44th Merwara Infantry
  The 44th Merwara Infantry was an infantry regiment of the British Indian Army. They could trace their origins to 1824, when the Sylhet Light Infantry was raised. This first 44th eventually became the 44th Gurkhas and later 8th Gurkha Rifles....
  
  
• 90th Punjabis
  90th Punjabis
  The 90th Punjabis were an infantry regiment of the British Indian Army. The regiment was raised in 1799 as a battalion of Madras Native Infantry. It was designated as the 90th Punjabis in 1903 and became 2nd Battalion 8th Punjab Regiment in 1922...
  
  

30th Indian Brigade

Commanding Officer, Major General C J Melliss

• 24th Punjabis
  24th Punjabis
  The 24th Punjabis were an infantry regiment of the British Indian Army. It was raised in 1857, as the 11th Regiment of Punjab Infantry. It was designated as the 22nd Punjabis in 1903 and became 3rd Battalion 14th Punjab Regiment in 1922...
  
  
• 76th Punjabis
  76th Punjabis
  The 76th Punjabis was an infantry regiment of the British Indian Army. It was raised by Captain Thomas Lane at Trichonopoly on 16 December 1776, as the 16th Carnatic Battalion. It was designated as the 76th Punjabis in 1903 and became the 3rd Battalion 1st Punjab Regiment in 1922...
  
  
• 2/7th Gurkha Rifles

33rd Indian Brigade

Commanding Officer, Brigadier R Wapshare

• 1/4th Btn Hampshire Regiment
• 11th Rajputs
  11th Rajputs
  The 11th Rajputs was an infantry regiment of the Bengal Army and later of the British Indian Army. They could trace their origins to 1825, when they were the 2nd Extra Battalion, Bengal Native Infantry...
  
  
• 66th Punjabis
  66th Punjabis
  The 66th Punjabis was an infantry regiment of the British Indian Army. It was raised in 1761 as the 7th Battalion of Coast Sepoys. It was designated as the 66th Punjabis in 1903 and became 2nd Battalion 1st Punjab Regiment in 1922...
  
  
• 67th Punjabis
  67th Punjabis
  The 67th Punjabis were an infantry regiment of the British Indian Army. They could trace their origins to 1759, when they were raised as the 8th Battalion Coast Sepoys....
  
  

Divisional Artillery

• 86 Heavy Bty Royal Garrison Artillery
  Royal Garrison Artillery
  The Royal Garrison Artillery was an arm of the Royal Artillery that was originally tasked with manning the guns of the British Empire's forts and fortresses, including coastal artillery batteries, the heavy gun batteries attached to each infantry division, and the guns of the siege...
  
  
• 104 Heavy Bty Royal Garrison Artillery
• 1/5th Hants Howitzer Bty Royal Field Artillery
  Royal Field Artillery
  The Royal Field Artillery of the British Army provided artillery support for the British Army. It came into being when the Royal Artillery was divided on 1 July 1899, it was reamalgamated back into the Royal Artillery in 1924....
  
  

Divisional Engineers

• 12 Field Coy Sirmur Imperial Service Coy, Sappers & Miners
• 12 Div Signal Coy

Further reading

• Perry, F.W. & Becke, A.F. (1945). History of the Great War: Order of Battle of Divisions: Indian Army Divisions Pt. 5B. London HMSO. ISBN 1-871167-23-X
• Haythornthwaite P.J. (1992). The World War One Sourcebook, Arms and Armour Press.
• Moberly, F.J. (1923). Official History of the War: Mesopotamia Campaign, Imperial War Museum. ISBN 1-870423-30-5