When war reignited between Konoha and Kumogakure, the ones who suffered most were not the citizens of the two great nations—Fire and Lightning—but the two small nations caught in between.
From a map's perspective, the Land of Lightning looks like a fallen bottle with a narrow neck.
If its long southwestern strip is the bottleneck, then the only nation touching it—the Land of Frost—acts like a cork plugging that neck, serving as Kumogakure's only passageway to the rest of the continent.
As for the Land of Hot Water, which borders the Land of Fire, its terrain is equally critical—like a thick shield guarding Fire Country's entire northeastern region, taking the brunt of Kumogakure's spearhead on Konoha's behalf.
One could say the locations of Frost and Hot Water make them natural battlefields.
Just as Nagato would say many years later:
"Great nations never care about the suffering of small nations."
After war erupts, what the leaders of great nations consider is always the same—how to keep the flames away from their homeland and minimize the harm to their own people.
As for how the small nations feel?
Who cares?
Senju Mori was no exception. Rationally speaking, he would never choose to let fighting take place inside the Land of Fire.
Leading his main force personally, he crossed the Fire Country border without hesitation and turned the Land of Hot Water into Konoha's frontline.
All indirect losses brought by war would be shifted entirely onto the weak Land of Hot Water.
...
A few days later
In the northeastern region of the Land of Hot Water, an enormous temporary encampment had been erected.
This nation, known for its hot springs and scenic beauty, now carried an oppressive atmosphere of war.
Dense forests had been cleared to create vast open space.
Hundreds of tents were put up within a single day, with several wooden buildings constructed at the center using local materials.
Although the Land of Hot Water had its own village—Yugakure—its shinobi population was tiny and its strength feeble. Most tasks were normally passed to Konoha anyway.
With war breaking out, this minor village—unable to secure even its own mission quota—could only curl up silently in its corner, playing dead while its country became a battleground for superpowers.
The daimyo of Hot Water issued a diplomatic protest to the Land of Fire, condemning Konoha's "barbaric actions"… only to be utterly ignored.
Reality proved that discrimination against the weak existed not only among shinobi villages but also among nobles and daimyo.
Since Senju Mori did not need to fight on multiple fronts, his available forces were quite substantial.
Aside from the 1,000+ shinobi he brought, he was reinforced by several hundred soldiers from the former northeastern border defense—altogether around 1,400 shinobi.
And this was only the force prepared for a localized conflict.
If Kumogakure chose to expand the war, Senju Mori could easily summon more reinforcements from the village.
In a one-on-one conflict, Konoha's greatest advantage was its manpower.
In a typical shinobi war, jōnin were irreplaceable elites, but main forces were composed of chūnin and veteran genin.
Unless circumstances were absolutely dire, no shinobi village would be foolish enough to send newly graduated academy students to the battlefield.
Kids who only knew the Three Basic Techniques would do nothing but raise the casualty count—they could not meaningfully affect the fight between two major villages.
...
Inside the tent-made command center, a jōnin knelt before Senju Mori and reported the newest information:
"Hokage-sama, a large number of Kumo shinobi have appeared within the Land of Frost. Several squads have already crossed the border and engaged our forces…"
Inside the tent, aside from Senju Mori himself, several shinobi from the Nara and Senju clans were present, assisting him in analyzing the latest intel and processing the documents being delivered from various locations.
Just as Senju Mori had anticipated, the Third Raikage would never agree to the harsh terms he proposed. After the envoy returned, the Raikage immediately mobilized a large shinobi force and launched a surprise, undeclared war on Konoha.
And since Kumogakure likewise refused to let its own homeland become a battlefield, their main forces left the Land of Lightning and advanced into the neighboring Land of Frost.
Unlike straightforward samurai, shinobi warfare is far more complex—and far more precise.
When a war begins, it is never two armies clashing head-on, hurling ninjutsu at each other in open fields. Instead, it starts with covert engagements between small squads—probing, testing, ambushing.
Infiltration, assassination, intelligence gathering, blowing up roads, cutting off supply lines…
Shinobi use their own special-operations methods to weaken the enemy off the main battlefield, sometimes even winning the entire war through these indirect tactics alone.
More than twenty years later, the "Battle of Kannabi Bridge" during the Konoha–Iwagakure conflict would become the most classic example of this.
Only when these small-squad skirmishes reach a certain intensity, and neither side can gain a decisive advantage, does the war escalate toward a final, large-scale confrontation.
Compared to the Third Raikage—eager to gain prestige and seize benefits from the war—Senju Mori had already firmly established himself as Hokage. He could afford to wage a prolonged war of attrition against Kumogakure.
Thus, he was in no rush to arrange his forces for a full confrontation or push toward a final showdown.
In fact, as soon as he arrived at the front line, his first order was to construct defensive fortifications.
Using the main Konoha encampment as the anchor point, he ordered large-scale Earth Release fortifications to be built, and had the forests along the borders of the Hot Water and Frost countries filled with barriers and traps.
At the same time, elite teams composed of jōnin and special jōnin were sent to infiltrate the Land of Frost to gather intelligence on Kumogakure's movements.
Among the several squads assigned to this dangerous mission was the "Special Tactical Unit" led by Danzo.
Senju Mori would not deliberately mislead Danzo with false intel, but Danzo's unit would undoubtedly receive the most dangerous, most difficult missions in the war.
Most of the remaining jōnin were paired with chūnin to form standard four-to-eight-man combat squads, tasked with laying more traps and hunting down Kumogakure shinobi who infiltrated the Land of Hot Water.
Konoha possessed the Hyūga's Byakugan, the Aburame clan's insects, the Inuzuka clan's ninken, and a variety of secret techniques…
In terms of sensory capability, they far surpassed Kumogakure, whose combat system was overwhelmingly straightforward and power-focused.
And Kumogakure, restricted by geography, had no choice: unless they were willing to cross the sea and risk severing their own supply lines, they had to break through the borders of Frost or Hot Water. There was no third route.
While Senju Mori issued orders in the command tent, he was also prepared to personally take the field and face the Third Raikage.
He wanted to see just how Kumogakure intended to break the stalemate and keep this war against Konoha going under such conditions.