The mortar turrets need to be controlled at all costs.
The terrain around the turrets prevents much escape.
The planet is extremely rich in minerals, which both the Republic and Empire need in this time of war. The beach is the most crucial, not only because it decides who has the advantage in the battle to contrl Denova, but because three prototype mortar turrets have been planted there. Forces need to be able to control and utilize the turrets on the opposition to have any chance of driving the enemy off the beach.
Both sides have set up temporary safe zones on the beach, heavily fortified so that neither can be invaded or destroyed. Shuttles with reinforcements are ferried to these safe zones constantly.
The terrain around the mortar turrets is high, rocky, and dangerous to all personnel who are not Force-sensitive, meaning that escape for forces with heavy machinery, weaponry and armor is almost impossible. People that are sent to the beach are stuck there until a winner to the conflict has been decided.