Using Phase Lines and Objectives in a Terrain Plan

Phase lines and objectives transform a terrain plan from a geographic reference into a tactical control tool. They give the commander the ability to sequence the operation, synchronize movement across multiple elements, and track progress in real time.

What Are Phase Lines?

Phase lines (PLs) are lines on the map drawn perpendicular to the direction of attack or movement. They divide the operational area into phases. Elements report when they pass phase lines, allowing the TOC to track the battle without requiring constant communication.

Phase lines are for control, not for stopping. An element does not halt at a phase line unless specifically ordered to. It reports passage and continues.

Step 1: Draw Phase Lines in Dark Dot

1. Open your Terrain plan and select the line feature type
2. Draw the phase line across the map at a recognizable terrain feature (road, ridgeline, stream — something that's easy to identify on the ground)
3. Label it: "PL ALPHA", "PL BRAVO", etc. Use NATO convention: letters in order of expected passage
4. Set the line color to a consistent scheme (phase lines are typically red in NATO graphics)

Tip: Anchor phase lines to identifiable terrain features. A phase line across open desert with no reference points cannot be confirmed on the ground.

Step 2: Place Objectives

Objectives mark what must be achieved — they are tied to specific locations on the ground.

1. Add a point or zone feature at the objective location
2. Set the feature type to match: point for a building or specific grid, polygon for a compound or hilltop
3. Link the objective to an operation objective in the sidebar:
   • Assign the responsible team (unit)
   • Set priority (1 = highest)
   • Set status: Planned → Active → Complete

Naming conventions: Use alphanumeric codes (OBJ HAMMER, OBJ ANVIL) that avoid revealing tactical intent if intercepted.

Step 3: Control Measures

Beyond phase lines and objectives, add these control measures to complete the terrain plan:

Measure	Feature Type	Purpose
Line of Departure (LD)	Line	Start line for the assault
Limit of Advance (LOA)	Line	Maximum forward advance authority
Coordinated Fire Line (CFL)	Line	Forward limit of indirect fires
No-Fire Area (NFA)	Polygon	Area where fires are prohibited
Engagement Area (EA)	Polygon	Area where enemy is to be destroyed
Assembly Area (AA)	Polygon	Staging area before the operation

Step 4: Synchronize Phase Lines with Objectives

A phase line only has value if it synchronizes multiple elements. For each phase:

1. Define which elements must reach the phase line before the next phase begins
2. Link the phase line passage to an event trigger: "When all elements report passing PL BRAVO, commander authorizes assault on OBJ HAMMER"
3. In Dark Dot: use the objective panel to update status in real time as elements report passage

Step 5: Build the Timeline Overlay

After placing control measures, annotate the expected time at each control measure:

• H-Hour: Time of assault on the main objective
• PL ALPHA by H-3: All elements cross the Line of Departure by 3 hours before H-Hour
• PL BRAVO by H-1: All elements at the assault position by 1 hour before H-Hour

Mark time annotations in the route or objective description fields so they're visible during briefing.

Briefing the Terrain Plan

The terrain plan is your primary briefing visual. During the OPORD brief:

1. Orient the audience to the map (north, scale, key terrain features)
2. Show the AO boundary and objectives
3. Walk each phase line in sequence, explaining the trigger and reporting requirement
4. Brief the fire support control measures (CFL, NFA) to prevent fratricide
5. Show the CASEVAC route and collection point

A briefed terrain plan should allow every subordinate leader to execute the mission without looking at the map again — if that's not possible, the plan is too complex.