| collier | a ship designed to transport coal |
| commandeer | officially take charge of a vehicle, vessel, building, supplies or equipment for a military purpose |
| commerce raiding | a form of naval warfare that disrupt logistics of the enemy on the open sea by attacking its merchant shipping |
| compensation | money or anything given as an equivalent to make amends for losses or damages |
| conscription | when citizens are made to join their country's military force, such as the army |
| contingent | a group of military personnel serving on the same side or for the same cause |
| convalesce | to rest and recover health after an illness or operation |
| convoy | a group of ships with an escort of warships, or a group of vehicles travelling together with a military escort |
| cordite | a smokeless explosive substance used in bombs and guns |
| cot case | a person too ill to leave their bed |
| counter-attack | a military attack in response to an attack |
| decoration | an official title or honour given to someone, usually in the form of a medal, as a reward for military bravery |
| degenerate | to become worse in some way |
| delegation | a small group of people sent to a place to have talks with other people as representatives of a larger group of people |
| demobilise | to release troops from military service - demobilisation (noun) |
| deploy | to organise and position troops, weapons or resources ready for action - deployment (noun) |
| descent | a person's family background, especially their nationality or social status |
| deserter | someone who leaves their job in the armed forces without permission |
| destroyer | a small, heavily armed warship |
| detachment | a group of soldiers sent away from the main group to do a special job |
| digger | an Australian or New Zealander, especially a soldier; often used as a term of address |
| diorama | a miniature three-dimensional scene with models of figures arranged against a background |
| dirigible | an airship, such as a zeppelin |
| disembark | to unload goods or passengers from a ship or aeroplane |
| dismount | to get down from a bicycle or horse |
| dispatch | a message or report that is sent by army officers or government officials to their headquarters - also 'despatch' |
| diversionary | describes an action to distract the enemy from the main point of attack |
| dogfighting | an aerial battle between opposing fighter planes |
| dominion | a nation that was part of the British Empire but had its own government e.g. Australia from 1901 to 1953 |
| dysentery | an infection of the intestine with bacteria or protozoa, characterised by severe diarrhoea |
| egalitarian | supporting the idea that all people are equal and should have the same rights and opportunities |
| embark | to load goods or passengers onto a ship or aeroplane |
| enact | to make a proposal into a law |
| encampment | a group of tents in a particular place, especially those used by soldiers |
| enlist in | to join a country's military force, such as the army - enlisted in, enlisting in; also enlistment (noun) |
| enteric fever | another name for typhoid fever, an infection caused by ingestion of Salmonella typhosa bacteria with food or water |
| escort | one or more guards, soldiers, vehicles or vessels who accompany others for protection, guidance or restraint, or as a symbol of honour |
| eugenics | the study of methods to improve the human race by selecting parents who will produce children with desirable traits |
| euthanise | to kill a person or animal painlessly, such as to relieve suffering from an incurable illness |
| expeditionary | relating to a journey undertaken for an exploratory or military purpose |
| feint | a mock attack or military movement designed to distract an adversary |
| flagship | the most important ship in a fleet, on which the commander of the fleet sails |
| Flanders | a World War I battle area in Belgium's East and West Flanders, the Netherlands' Zeeland and France's Nord |
| fleet | a group of ships organised to act together, such as fight a battle |
| fragmentation | describes a weapon designed to explode into many small pieces, especially an anti-personnel weapon |
| front | a line where two opposing military forces are facing each other |
| gallantry | bravery shown by a person who is facing danger, for example when a soldier is fighting in a war |
| gangrene | the decay in a part of a person's body if the blood stops flowing to it, as a result of illness or injury |
| garrison | a group of soldiers who guard the town or building where they live |
| Great Britain | refers to the island of England, Wales and Scotland, and its surrounding isles, but not Northern Ireland - 'Britain' for short |