What is an essential feature of a 'U-shaped' machine gun fighting position?

The essential feature of a 'U-shaped' machine gun fighting position is that it provides wide fields of fire. This configuration allows the machine gunner to cover an extensive area without obstruction, optimizing their ability to engage targets effectively at various angles. The 'U' shape typically offers overlapping fields of fire, which is crucial for ensuring coverage of a specific sector while minimizing dead zones. This design not only enhances the firepower concentration but also allows for better maneuverability of the gunner and the potential for multiple gunners positioned to support each other efficiently.

While other configurations might allow for close-range engagements or facilitate communication, the distinctive advantage of the 'U-shaped' setup is primarily its ability to maximize coverage, thereby enhancing the overall effectiveness of the defensive or offensive capabilities of the unit.