A phase in combat is usually a period within a military operation of a longer duration that is a part of a serial chain of logically connected activities planned to culminate in a defined objective or goal.
A phase is usually marked by achievement of significant intermediary objectives, such as tactical within an engagement. A phase may be either limited by time allocated for its execution, or unlimited in time, and defined only by achievement of the objective.
At the strategic level, a phase continue for years. Not all phases of combat include fighting between armed forces. Phases can, and usually do overlap, and sometimes can be planned for parallel execution, often as part of deception planning.
Phases typically found in offensive military operations are:
Preparation
Intelligence gathering phase
Operations planning phase
Logistics management phase
Deception and counterintelligence phase
Assembly phase
Conduct
Initial (combat assault) phase
Breakthrough phase
Exploitation
Follow-on (support) phase
Pursuit phase
Objective security phase
Position consolidation phase
Defensive phase
Reorganisation phase
A lull in combat (usually unplanned) Stability Enable civil authorities