There’s nothing like a war and battle scenes to get the blood flowing and the reader’s imagination and vicarious enjoyment going. Adversely, there’s nothing like volumes of context of how the war came to be and why the battles are fought the way they are that’ll drive away all but the most diehard military history fans. There’s a precarious balance between warfare’s cold logistics and the personal glory and trials of heroic individuals. The former is the concept by which real wars are planned and won whilst the latter is just so darn fun to read about. Nobody bends their bar of enjoyment to hear about the wanting quality of issued shoes, particularly around the sole, but everyone understands one man can’t win an entire war. The writer’s issue becomes how to reconcile these conflicting forces.
Always the first consideration is: what kind of story are you writing? If you have a smaller scale or youth focused story then the personal heroics will likely take center stage with the flash and empowerment kids crave. Call it fanciful to reduce the war’s moral complexities and strife to a final duel between good and evil, you’d be just, but if the violence is used as the trial and resolution to a single moral question (i.e. peaceful coexistence over bloody subjugation) then let the kids play pretend as they dip their toes.
Down the spectrum lay the grand strategy, historical, satellite zoomed out image of war. There we see the outlying issues shaping the conflict like rapid ideological change brought on by a slew of technological advancements. This mode of observation can be dry/academic discussions about what amount of the political change can be attributed to settlers surviving in rugged new lands an ocean away from their king and their reevaluations on the contributions and necessity of monarchy. It’s an interesting debate for the right mind and presents weighted issues we parallel in our modern world, but absent are any human emotions we can connect with and have carry us to the conclusion and the author’s answers.
The second consideration is: how much detail does the story require? Is the war a side effect of the story or wrapped in the central premise or a backdrop to a different conflict? Who’s narrating? If the war is shown through the sights, sounds, and smells of a single soldier or low ranked officer then the detail would center on small unit drill, tactics, formations, and usage on the battlefield, not counting the soldier’s everyday life on the march and at camp and on leave. If the story focuses on a family escaping the war as it strides toward them then consider the movements of armies and human migratory patterns (amongst the local geography and climate) along with the modes of destruction and diseases which shadow armies. If there are scenes of the general’s staff planning a campaign then be ready to explain why the army marches in its inevitable direction after weighing the possible risks and rewards, knowns and unknowns and known unknowns.
Getting specific, the third consideration is: what type of warfare and combat happens in your story? This is a matter of the time period, theater, technology, and magic and assorted fantasy elements if present. Different time periods have particular ideologies of what makes a good soldier from bravery to weapon proficiency to discipline. Hand to hand combat at the end of a spear means sharp, violent clashes followed by long interludes of relative calm as one side exploits the victory and the other rebuilds and reorganizes. More modern warfare with populous nation states means renewing and reinforcing armies upon armies leading to persistent, attritional combat that may reshape the nation. There are the intricate tactics of naval combat with the desire to maneuver with a tailwind achieve local superiority. If you’re introducing fictional weapons, beasts, and craft, consider how warfare would adapt. If magicians can roll the ground like a wave there’s little incentive for fortifications unless you can make them highly earthquake resistant.
The first solution, obvious yet necessary, is research. As a rule of thumb, you should never write at the last extent of your knowledge on a given real-world study. If you don’t understand why your story element is the way it is and how it came to be then you don’t know what you’re talking about. Keeping with the military theme, take the infantry line formation—a way of grouping soldiers together for maximum firepower, psychological benefit/intimidation, cohesive movement, and protection against cavalry. This is all good and basic but when the forward-thinking protagonist calls the infantry line formation a relic, he might look the fool instead. Unless the entire army sports conical bullets and bolt action rifles then there’s not a more practical manner to shoot at the enemy. Additionally, this assumes the infantry line is an old formation but anyone with a cursory desire to check Wikipedia will find out the line formation was an evolution of the outdated pike and shot formations of early firearm usage which lasted about two hundred years. The most innocuous narrative comment can nip at the suspension of disbelief. Even if you just want a cool swordfight it’d be helpful to study real-life swordfighting techniques and the weapons and armor and that’s an easier task now than ever with the internet. If you can safely practice with weapons I’d highly recommend it for internalizing sensations that elude the page. Unless you have a strong understanding of the subject beyond what you present in the final work you’re leaving the door wide open for flaws. If you want to write about it then learn till you have authority.
On the story structure, mix a bit of both ends of the spectrum and land somewhere in the center. Unless you try you’ll never create a war story that’s solely the exploits of an individual or explanations of the conflict in totality. Invariably you’ll develop characters worth seeing in action and find reasons for them to act. The classic quiet farm town hero wants to make the world safe for him and his family by defeating the evil tyrant. It’s not exceedingly political but there’s the barest thread of where power and domains lie.
Likewise, the cold trends and forces which propagate conflict don’t always align perfectly leaving the person or group who ultimately make decisions to weigh the best choice with their fallibility, personal interests, financial stakes, etc. Great men may shape the world but they can only shape the world they’re given and only as far as the world can sustain. Napoleon wasn’t going to commit the earth to eternal clean energy in the nineteenth century.
What I’ve found as a good template to expand upon is to give the character desires and agency, however little or great, and the conflict reflective agency. With that you can make any character’s actions self-motivated as their impact on the conflict gives their choices meaning and the change in the conflict reacting upon them gives both consequences and a clear path to continue the story in a smooth back and forth but-therefore progression. Nothing exists in a vacuum; a character and their world stand upon the same rock.
In effect, have the average man suffer economic disparities including lack of food before being drafted to war. Officers on the training grounds instill the message that victory will end the recruit’s family’s suffering through conquest of rich farmlands and waterways. The recruit therefore conceives of each pained footstep toward that goal his noble duty. Meanwhile, the general contemplates the morale issue in his half-starved army and reasons it to be vulnerable to a prolonged campaign. However, he fears a single significant loss inside enemy territory will cut off his tenuous supply line and lead to mass desertion and suffering. But at a loss for a better strategy, and cursing the martial inventiveness he didn’t inherit from his father, he marches the men off in a bold advance.
If you have an idea of where the story progresses from here take it and run.