A set piece attack involves a deliberate assault on a known enemy which occupies a particular piece of terrain.To a certain extent, enemy strengths and dispositions on the terrain are known. Set piece means that there is time to develop a co-ordinated plan of attack, which will consider the best possible scheme of manoever given: the nature of the terrain, own strength/capabilities and those of the enemy.The scheme of manoever may involve one or more of: a frontal attack, a flanking attack,or an envelopment from the rear.
This type of attack will involve the co-ordinated use of all assets and fires. This includes infantry, armour, engineers, artillery, engineers and airstrikes. Reserve formations of armour/infantry are held in depth to exploit or reinforce success as the attack progresses. In some cases the plan may also feature a deep insertion of troops in the rear by helicopter or airdrop, in order to isolate the battlefield/deny enemy reinforcement routes/cause a turning action (where the enemy must divert resources from the front to protect his rear areas). The attack may be preceeded by artillery fire and air strikes before the actual assault time, which is known as H Hour(the time that troops cross the line of departure/LD). Air and artillery fires can be pre-planned for certain designated targets at a designated time in relation to H Hour.
Once the assault commences, fires are also employed on call as the situation develops. In addition to fires which are co-ordinated with the scheme of manoever, and which are generally designed to neutralize the enemy's ability to respond, fires will also be employed to isolate the battlefield/prevent the enemy's ability to move and respond, and to attack enemy artillery and reinforcements in depth. A supporting attack on another objective can also be used to assist the main attack, by confusing the enemy as to our main effort and tying-up reserves which he might otherwise wish to shift to the main attack.
A deliberate attack will be executed at a time and place most favourable to our success, with due consideration of the factors of: mission, enemy, own troops, terrain and weather. Key elements are the timing of the attack, and our ability to mass a preponderance of our own forces/assets at the time and place chosen for the assault. A deliberate attack also affords the maximum opportunity to concentrate forces, plan fires, conduct reconnaisance, gain intelligence and prepare the troops for battle.
That is the high level/Command and Staff College answer to your question. Actual troop deployments/assault formations/schemes for fire and manoever are another topic for a discussion of tactics, at section/platoon/company/battalion levels.
