'On This Day' from culturepics.org

BRITAIN BEFORE THE FIRST WORLD WAR
21 May 1914
Imperial War Museum

Bootle Riot Sequel
21 May 1915
Imperial War Museum

Captain Ernest Lynton Large. Unit: 1/5th (City of London) Battalion, The London Regiment. Death: 21 May 1915 Western Front
Died 21 May 1915
Imperial War Museum

Captain Frederick Charles Waterfield. Unit: 45th Rattrays Sikhs, attached to 15th Ludhlana Sikhs, Indian Army. Death: 21 May 1915 Wounded 19 May 1915 by a shrapnel bullet, died in Bethune Hospital Western Front
Died 21 May 1915
Imperial War Museum

Captain Geoffrey Francis Robinson. Unit: Kings Shropshire Light Infantry, attached to 1st Battalion, 4th Gurkha Rifles. Death: 21 May 1915 Western Front
Died 21 May 1915
Imperial War Museum

Captain Maurice Aldcroft Phillips MID. Unit: 35th Battery, Royal Field Artillery (CWGC lists 31st Battery, RFA). Death: 21 May 1915 Western Front
Died 21 May 1915
Imperial War Museum

Lance Corporal Walter Neal T/835. Unit: Army Service Corps, West Riding Division. Death: 21 May 1915.
Died 21 May 1915
Imperial War Museum

Lieutenant Espine Montgomery Picton-Ward. Unit: 16th Battalion, Canadian Infantry (Manitoba Regiment, Canadian Scottish). Death: 21 May 1915 Killed in Action leading his men in a charge near Festubert Western Front
Died 21 May 1915
Imperial War Museum

Lieutenant Gordon Alexander Gordon Mackenzie. Unit: 16th Battalion, Canadian Expeditionary Force. Death: 21 May 1915 Western Front
Died 21 May 1915
Imperial War Museum

Lieutenant The Hon. Arthur George Coke. Unit: Royal Naval Volunteer Reserve, Armoured Car Division. Death: 21 may 1915 Gallipoli
Died 21 May 1915
Imperial War Museum

Second Lieutenant Curwen Vaughan Rawlinson. Unit: 3rd (Reserve) Battalion, attached to 1st Battalion, Dorsetshire Regiment. Death: 21 May 1915 Hill 60 Flanders Western Front
Died 21 May 1915
Imperial War Museum

Second Lieutenant George Bruce Joy. Unit: 3rd Battalion, Welsh Regiment, attached to 1st Battalion, Highland Light Infantry. Death: 21 May 1915 Western Front.
Died 21 May 1915
Imperial War Museum

Sub Lieutenant Geoffrey William Stopford-Sackville. Unit: Royal Navy, HMS Ribble, Torpedo Boat Destroyer. Death: 21 May 1915 Died from wounds received at Gallipoli on 25 April 1915 Gallipoli/Dardanelles
Died 21 May 1915
Imperial War Museum

THE SECOND BATTLE OF ARTOIS, MAY-JUNE 1915
21 May 1915
Imperial War Museum

AERIAL PHOTOGRAPHY ON THE WESTERN FRONT DURING THE FIRST WORLD WAR
21 May 1916
Imperial War Museum

BRITISH OFFICIAL PANORAMAS OF THE WESTERN FRONT 1914 - 1918
21 May 1916
Imperial War Museum

GERMAN PRISONERS IN THE ALLIED CAPTIVITY, 1914-1918
21 May 1916
Imperial War Museum

Lieutenant Bernard Scott. Unit: 15th Battalion, London Regiment (Prince of WalesOwn Civil Service Rifles). Death: 21 May 1916 Missing at Vimy Ridge Western Front
Died 21 May 1916
Imperial War Museum

Private Noel Francis Coakeley 3085. Unit: 7th Platoon, B Company, 1st/15th Battalion, London Regiment (Prince of Wales' Own Civil Service Rifles). Death: 21 May 1916 Missing in action Western Front
Died 21 May 1916
Imperial War Museum

Second Lieutenant Neville L Ames. Unit: 8th Battalion, London Regiment (Post Office Rifles). Death: 21 May 1916 Vimy Ridge, north of Arras Western Front
Died 21 May 1916
Imperial War Museum

An RAMC Stretcher-bearer: 'Just come from the Chemical Works, Roeux, 21st May 1917'
21 May 1917
Imperial War Museum

BRITISH OFFICIAL PANORAMAS OF THE WESTERN FRONT 1914 - 1918
21 May 1917
Imperial War Museum

Hilton Young, E., Lieutenant to IWM
21 May 1917
Imperial War Museum

PORTUGUESE EXPEDITIONARY FORCE IN FRANCE 1917
21 May 1917
Imperial War Museum

Private Stanley Reddall 269317. Unit: Worcestershire Yeomanry, attached to 1st/7th Battalion Sherwood Foresters. Death: 21 May 1917 Lens Western Front
Died 21 May 1917
Imperial War Museum

Rifleman Frederick S Cook 5036/322257. Unit: 2nd/6th Battalion, London Regiment (City of London Rifles). Death: 21 May 1917 Missing in action near Bullecourt Western Front
Died 21 May 1917
Imperial War Museum

Rifleman Henry G. Higlett 5776/322876. Unit: 5th Platoon, "B" Company, 2nd/6th Battalion, London Regiment. Death: 21 May 1917, missing in action, Western Front. Commemorated on the Arras Memorial.
Died 21 May 1917
Imperial War Museum

Rifleman John Albert Darvell 4930/322182. Unit: B Company, 2nd/6th Battalion, London Regiment (City of London Rifles). Death: 21 May 1917 Wounded and Missing in action believed Killed in action
Died 21 May 1917
Imperial War Museum