ATP-4-90 Brigade Support Battalion Download
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Chapter 4 4-8 ATP 4-90 18 June 2020 Figure 4-3. Example of a completed company sector sketch Leaders are involved in developing the sector sketch and ensuring that units execute it to standard. Units construct fighting positions to standard and ensure the fighting positions are mutually supportive with interlocking fields of fire. Units establish a final protective line across broad fronts or likely enemy avenues of approach. The final protective line is a selected line of fire where an enemy assault is halted by interlocking fire from all available weapons. The BSB S3 develops a coordinated, predetermined signal for Soldiers on the perimeter to shift fire to the final protective line. Once the final protective line is initiated, all Soldiers fire weapons at maximum cyclic rate along the line. Soldiers spare no ammunition in repelling the enemy. Fighting positions for both crew served weapons and individual weapon positions develop range cards, to standard, which in turn aid in developing situational understanding of the base terrain. The company compiles range cards from fighting positions using DA Form 5517 (Standard Range Card) to build sector sketches up to a complete company sector sketch. Figure 4-4 depicts an example of a completed range card using DA Form 5517. The BSB develops an obstacle plan as part of the base or base cluster defense. Units use obstacles to disrupt, turn, fix, and block an enemy’s progress. The BSB S-3 analyzes the situation and plans hasty or engineer emplaced obstacles to support the base defense. Companies in the base also develop their own internal company obstacle plan that nests with the BSB’s obstacle plan. Commanders integrate reinforcing obstacles with existing obstacles to improve the natural restrictive nature of the terrain to halt or slow enemy movement, canalize enemy movement into engagement areas, and protect friendly positions and maneuver. Units must integrate obstacles with fires to be effective. Improvement to defensive positions is continuous. Given time and resources, the defending force constructs additional obstacle systems in-depth, paying special attention to its assailable flanks and rear.