The perception of which targets were the most important changed, and at times it became preferable to strike at positions at long range: at assembly places, reserves, logistics, C3 and artillery, rather than the enemy’s front line. Such targets constitute for artillery the “deep” or long range battle. In the West today the battlefield is generally defined according to specific ranges: the close or contact battle refers to engagements within small arms range up to 300m and the contact battle extends to 4km. The depth battle is generally defined as the surface battle between 4 and about 30km, while the deep battle refers to the battle area beyond that. On today’s European battlefield, there is arguably no measurable FEBA and it is dangerous to lay down specific measurable zones. For the purposes of this study across time and transcending technological capabilities, the terms “close” and “deep” will be used primarily to indicate target type, for range is relative: for example, a CB target in the First World War might well be considered close today in terms of range, but CB targets then and now have generally been regarded as deep targets. The importance of close and deep artillery tasks has varied according to the prevailing concept of operations. The balance tipped most towards the deep battle in 1918, and to the close in the West in the Second World War, when aircraft assumed a role formerly the preserve of medium and heavy artillery.