Line/Square formations with automatic rifles and sentient vehicles?

Question

Is there any reasons a line/pike-square formation would be used with soldiers equipped with automatic rifles with bayonets?

The army also has sentient vehicles that can transport troops and fight on their own as well. The only caveat is that the army doesn't use towed artillery,

Their enemies will almost always have worse weapons then them. Their enemies will usual be a tech level from the High Middle Ages to Late 1800s with bolt action rifles. Their most common enemies are soldiers from the 1500s to mid 1800s. Also these enemies were transported from other worlds by some phenomenon no one can truly explain.

Not to mention that the soldiers in the line formation will have bullet resistant armor on, like cuirasses and magic gambesons.

Please give reasons why a line/pike formation would be used by troops equipped with automatic rifles.

Answer 1

If we're talking "magic gambesons" it could have something to do with the defensive magic that makes them bulletproof. The spell which grants them bullet-proofness requires a certain amount of magical energy (X), but each gambeson can only have (Y) amount of energy. However the spell can be daisy-chained via close proximity. So while 1 spell-enhanced gambeson cannot stop a bullet, 300 of them provide enough energy to make the whole formation essentially bulletproof. Classic "the whole is greater than the sum of its parts" logic. If you say the daisy-chain effect only holds at half a meter or less then it becomes tactically viable to cram your soldiers together into denser line/block formations.

Answer 2

Grouping your soldiers into tight groups has tactical and psychological advantages. Arranging those groups into specific formations, given the superiority of armor, mobility and weaponry does not seem to offer any advantage.

Psychologically, having armed friendlies nearby helps with morale. It supports courage and obedience to the chain of command. Tactically, it concentrates firepower and allows for cooperative defense.

On a higher strategic advantage and specific to your technological superiority, keeping your troops in groups allows you to recover fallen soldier bodies (weapons and armor) during any necessary retreat. This keeps those advanced tools out of the hands of your enemy and thus maintains your advantage.

Classical formations are mostly about maintaining clear lines of fire for soldiers who prior to enlistment, probably did not have much exposure to fire arms or coordinated tactics. If you can afford to equip your soldiers to the level of advantage which you apparently have, you can also afford to train them to use that advantage safely and effectively. They can always take up a formation when it would be advantageous for a particular combat engagement; but the is no need for them to maintain those formations during non-critical times.

Answer 3

Hostile Natives:

If the enemy armies are not the only threat the army has to deal with, then these tactics may make more sense. Angry civilians mobbing your ranks will be unable to flank and charge such ranks. Werewolf charges are terrifying, but can't penetrate the defenses before being mowed down or impaled on silver-tipped bayonets. And enemy auxiliaries of pony-mounted archers will find such positions a hard nut to crack.

Outstanding large bulletproof body shields could make a phalanx-type defense turn into the equivalent of a BTR-60, armored on all sides to what the enemy can deliver and allowing free return of fire through built-in gun ports. The ranks could stop on any slightly elevated point, interlock (possibly literally) shields, and let the enemy charge. The heavy equipment wouldn't be ideal for all uses, but a modest force facing numerous mediocre opponents might be able to lure them into repeated grinding charges.

If the enemy uses very powerful weapons (like horse-drawn artillery) these formations would be very dangerous. But as long as the enemy weapons aren't up to getting through a defense and your army has good enough defenses to thwart those that come at them, then the general lack of professionalism in forces from these periods could lend such an approach a real kick.