| Big Mom–Kaido alliance | |
|---|---|
| Name | Big Mom–Kaido alliance |
| Type | Military and political alliance |
| Formed | One Piece timeline (Wano Country arc) |
| Location | Wano Country and the New World |
| Leaders | Big Mom (nominal), Kaido |
| Allies | Beasts Pirates, Big Mom Pirates |
| Opponents | Straw Hat Pirates, Allies of the Minks and Kozuki, Minks, Kozuki Oden's loyalists |
Big Mom–Kaido alliance
The Big Mom–Kaido alliance was a strategic pact between two of the Yonko—Big Mom of the Big Mom Pirates and Kaido of the Beasts Pirates—formed to consolidate power in the New World and jointly seize territories such as Wano Country. It mattered because it threatened the balance of power among the Yonko, challenged the Straw Hat Pirates and their allies, and catalyzed the climactic conflicts of the Wano Country arc.
The alliance traces to the power politics of the New World where the Yonko compete for dominance. Kaido sought to create a vast army to open the closed nation and expand influence, while Big Mom pursued political marriages and territorial control. Their pact was brokered through mutual interests: consolidation of resources, the exchange of subordinate forces, and a proposed marriage alliance between the Charlotte Family and Kaido's retainers. The arrangement reflected the larger struggle against the rising influence of captains like Monkey D. Luffy and the reshaping of alliances after confrontations involving the Beasts Pirates, Big Mom Pirates, and remnants of the Whitebeard Pirates.
Politically the alliance combined Big Mom's extensive Charlotte Family network—spanning islands in Totland—with Kaido's military apparatus, the Beasts Pirates, organized into numbered divisions and headed by powerful commanders. Command authority remained largely autonomous: Big Mom maintained influence over her Sweet Commanders and the family's subordinates, while Kaido retained operational control in regions he claimed such as Wano Country. The pact included logistics sharing (ships, supplies, Devil Fruit assets) and a joint command for large-scale campaigns. Subordinate arrangements allowed transfer of personnel like the migration of Tontatta-era captains, the use of Gifters and SMILE troops, and cooperation with vassals such as On Air officials and local daimyo coerced into service.
In the Wano Country arc, the alliance was central: Kaido established a fortress at Onigashima and used Big Mom's forces to bolster numbers for the planned invasion of Kuri and domination of Wano. The pact's marriage component and promises of territory helped Kaido secure additional veteran commanders. The alliance precipitated the formation of the anti-Yonko coalition: Monkey D. Luffy's Straw Hat Pirates aligned with the Kozuki Family, Samurai of Wano, the Minks, and other regional forces to resist the occupation. The combined might of Big Mom and Kaido forced unconventional tactics, including infiltration, guerrilla campaigns by the Akazaya Nine, and coordinated naval strikes by the alliance's opponents.
Major confrontations included the siege of Onigashima and the multi-front Battle of Wano Country. The alliance's forces engaged the Straw Hat Pirates and allied samurai across Onigashima's tiers, leading to duels involving notable figures such as Kaido vs. Monkey D. Luffy and clashes with Big Mom's commanders. The use of Devil Fruit powers, Haki mastery, and massed SMILE armies produced large-scale attrition battles. Critical defeats, including the collapse of coordinated command when Big Mom and Kaido were separated during pivotal fights, undermined the alliance's effectiveness. The alliance also provoked naval and pirate faction responses from other Yonko and World Government concerns over regional stability.
Prominent leaders directly involved were Kaido and Big Mom, supported by lieutenants like Kaido's Allies and Big Mom's Sweet Commanders (e.g., Charlotte Katakuri, Charlotte Cracker). Subordinate forces included the Beasts Pirates divisions, the Big Mom Pirates crews, and SMILE-enhanced troops commanded by mid-tier officers. Local collaborators in Wano comprised Kurozumi Orochi's retainers and coercively aligned daimyo, while insurgent groups like the Akazaya Nine and Heart Pirates allies fought against them. Other named entities connected to the alliance episode included Trafalgar D. Water Law and remnants of the Worst Generation who helped destabilize Yonko coordination.
The alliance intensified the Yonko rivalry and accelerated shifts in regional power. Its failure weakened Kaido's perceived invincibility and diminished Big Mom's ability to project unchallenged authority into Wano, altering balance among top-tier pirate crews. The conflict exposed vulnerabilities in using mass-produced SMILE forces and reliance on coerced vassalage, prompting renegotiations among pirate factions and increased intervention by the World Government and Marines in post-war stabilization. The struggle also elevated figures like Monkey D. Luffy in global notoriety, contributing to changes in bounty hierarchies and future diplomatic calculations among Yonko and allied warlords.
After the collapse of the alliance in Wano, both Big Mom and Kaido suffered strategic losses: diminished manpower, fracturing internal loyalty, and reputational damage that encouraged defections among captains and subordinates. The aftermath reshaped alliances in the New World—some factions realigned toward opportunistic coalitions while others sought protection under remaining Yonko or the Red Line-adjacent powers. Wano's liberation reinforced samurai autonomy under the restored Kozuki Family and served as a political example of resistance to imperial pirate domination. The episode left a lasting imprint on maritime order, succession struggles within pirate crews, and the unfolding quest for the One Piece.