25 July
Serbia annonces a general mobilization.
30 July
Russia annonces a general mobilization.
31 July
Austria-Hungary annonces a general mobilization.
1st August
France annonces a general mobilization.
Germany declares war on Russia.
3 August
Germany declares war on France.
4 August
German Army invades Belgium.
Great Britain declares war on Germany.
5 August
New Zealand declares war on Germany.
12 August
Arrival of the British expeditionary force in Boulogne-sur-Mer (France, Pas-de-Calais).
Start enlistment to form a New Zealand expeditionary force.
29 August
New Zealand Army captures German Samoa.
6-9 September
Battle of the Marne (France).
14 October
Departure of the expeditionary force from New Zealand.
23 October
First mining operations at Vermelles (France, Pas-de-Calais) by the French sappers.
18 November
Early French mining actions in Argonne (France, Lorraine).
15 December
John Norton-Griffiths, a Member of Parliament and civil engineer, sends an offer to create Tunnelling Companies in United Kingdom.
20 December
10 German mines of 50kg explode beneath the British trenches at Festubert (France, Pas-de-Calais).
26 January
20 German mines destroy British frontline at Cuinchy (France, Pas-de-Calais).
19 February
British Government accepts John Norton-Griffiths' offer to raise British Tunnelling Companies.
21 February
Early mining operations of the 170th Tunnelling Company at Hill 60, near Yper (Belgium).
25 April
Landing of Australia and New Zealand soldiers at Gallipoli (Turkey).
25 May
A New Zealand mine explodes at Quinn's Post which start the underground warfare at Gallipoli.
24 July
British Tunnellers of the 174th Tunnelling Company relieves French sappers at Carnoy, Fricourt, Maricourt and La Boisselle (Somme).
10 September
British Government sends an appeal to Canada, South Africa, Australia and New Zealand to raise Tunnelling Companies in the Dominions.
17 September
New Zealand is the first Dominion to announce formation of a Tunnelling Company.
Early enlistment to form the New Zealand mining corps.
11 October
Start of the New Zealand Tunnellers' training on the Avondale Racecourse, near Auckland (New Zealand).
18 December
The New Zealand Engineers Tunnelling Company leaves Auckland on board the S.S. Ruapehu.
8-10 January
Ruapehu call in at Montevideo (Uruguay).
End of January
Ruapehu call in at Dakar (Senegal).
3 February
Arrival of the New Zealand Engineers Tunnelling Company at Plymouth (Great Britain).
Start of the last training before departure to France.
10 March
Arrival of the New Zealand Tunnellers in Le Havre (France, Normandie) becoming the first New Zealand soldiers ont the Western Front.
15 March
The New Zealand Engineers Tunnelling Company relieves the French 7/1 compagnie d'ingénieurs territoriaux in the Labyrinth sector, between Roclincourt and Ecurie (France, Pas-de-Calais).
29 March
The New Zealand Tunnellers exchange their position with the 185th Tunnelling Company and fight henceforth at Chantecler, a kilometer South of their old sector.
7 April
First German underground offensive against the New Zealand Tunnellers.
5 May
Four New Zealand mines explode becoming the first New Zealand Tunnellers' underground action.
4 June
Explosion of four German mines near and beneath the British frontline whose three form craters on the surface.
Summer
Development of the New Zealand underground system creating an effective underground defense at Chantecler.
5 November
Exploration of the first underground quarries located in Saint-Sauveur and Ronville faubourgs in Arras.
15 November
End of the underground warfare for the New Zealand Tunnellers.
Early New Zealand connexion works in the underground quarries in Ronville (Pas-de-Calais, Arras).
25 November
Early connexion works of the men of the 184th Tunnelling Company in Saint-Sauveur (Pas-de-Calais, Arras).
9 December
43 Māoris of the Māori Pioneer Batallion reinforce the New Zealand Tunnellers.
4 January
Start putting in electricity in the quarries.
Mid-January
End of the connexion works in the entire underground system in Arras.
24 January
Installing direction signs in the underground system.
25 January
Early works to organize a tramway line in Ronville and Saint-Sauveur systems.
14-16 March
German withdrawal on the Hindenburg line making it impossible to attack from the Ronville System.
3 April
Electricity is installed and tested in the whole system beneath Arras.
9 April
Beginning of the Battle of Arras.
Opening of the three tunnels located at the end of Saint-Sauveur system allowing infantrymen to appear suddently in the German trenches.
5 May
Early development beneath trenches located between Gavrelle and Roeux, East of Arras by the New Zealand Tunnellers.
Summer-Automn
Digging dug-outs beneath British trenches by the New Zealand Tunnellers.
5 November
Explosion of a damage ammunition stock at Wanquetin by the New Zealand Tunnellers.
Winter
Continuing constructions beneath trenches by the New Zealand Tunnellers.
21 March
Large German offensive at Arras.
Start of trenching South-West of Arras for the New Zealand Tunnellers.
May-July
Back to digging underground constructions beneath trenches for the New Zealand Tunnellers.
14 July
Departure of the New Zealand Tunnellers from Arras.
15 July
Arrival of the New Zealand Tunnellers at Marieux (France, Somme).
17 July
Early digging dug-outs beneath trenches at Marieux.
20 August
End of the underground works for the New Zealand Tunnellers.
28 September
Start construction of a military bridge at Havrincourt (France, Nord).
5 October
End of the Havrincourt bridge construction becoming the longest bridge erected on the Western Front.
Automn
Erection of various military bridges.
11 November
Signing of the Armistice in the Compiègne Forest (France, Oise).
Early December
Demobilization of the first New Zealand Tunnellers.
21 January
Demobilization of the New Zealand Engineers Tunnelling Company.
30 January
Arrival of the New Zealand Tunnellers in Great Britain.
14 March
Departure of the New Zealand Engineers Tunnelling Company from Great Britain.
23 April
Arrival of the last New Zealand Tunnellers in Auckland.
24 April
Dissolution of the New Zealand Engineers Tunnelling Company.