The Treaty of Sinj was a landmark peace agreement signed on May 27, 1921, formally ending the Kresimirian Unification War (1918–1921). Negotiated in the immediate aftermath of the decisive Battle of the Brod Ford, the treaty was signed in the Kresimirian capital of Sinj between the victorious Centralist Faction and the defeated expeditionary government of Boskenmark and the Sprodvice Provisional Directorate.
The treaty is recognized as the foundational legal document of the modern Divine Republic of Kresimiria. It established the Republic’s international borders, formally dissolved the secessionist Sprodvice Provisional Directorate, and legally annexed the Pravoslavic-majority southern territory of Moraviskameja (designating it as District X). While the treaty successfully ended conventional state-on-state warfare on the Nastavak continent, its failure to address the political rights of the Bosken minority directly sparked the forty-year BRC-21 insurgency.
Historical Background
By May 1921, the three-year civil war that followed the collapse of the Vosti Empire had reached its climax. The Centralist Faction, commanded by General Dominik Loncar, had systematically dismantled the Sprodvice Provisional Directorate’s organized military during the grueling Siege of Ravna Skrad.
In a desperate bid to save the south from Sanctian domination, the neighboring state of Boskenmark launched a conventional military intervention in March 1921. However, this expeditionary force was completely outmaneuvered and routed by Loncar at the Battle of the Brod Ford (May 18–20, 1921). Fearing a retaliatory Kresimirian invasion across the Brod River into their own territory, the Boskenmark government immediately sued for peace.
Terms of the Treaty
The negotiations took place over five days in the Grand Hall of Sinj. The Kresimirian delegation was led by Filip Novak, head of the Revolutionary People’s Council. The Boskenmark delegation was severely disadvantaged, negotiating under the explicit threat of Loncar’s artillery batteries massed on their border.
The final treaty included several non-negotiable Centralist demands:
- Territorial Demarcation: The international border between Kresimiria and Boskenmark was permanently fixed at the Brod River.
- Annexation of the South: The entirety of the disputed Moraviskameja region, including the city of Sprodvice, was legally recognized by Boskenmark as sovereign Kresimirian territory.
- Dissolution of the Directorate: Boskenmark agreed to cease all recognition and material support for the Sprodvice Provisional Directorate, formally classifying its surviving members as stateless combatants.
- Military Withdrawal: Boskenmark was forced to demilitarize a five-kilometer “buffer zone” on their side of the Brod River.
Notably absent from the negotiations were any actual representatives of the Bosken rebels, such as Captain Lev Ruka, whose irregular forces were entirely cut out of the diplomatic process.
Signing and the Birth of the Republic
The treaty was formally signed on the morning of May 27, 1921. Immediately following the signing ceremony, Filip Novak stepped onto the balcony of the Grand Hall in Sinj and proclaimed the establishment of the Divine Republic of Kresimiria.
The signing date of May 27 was permanently codified as a national holiday in Kresimiria (“Republic Day”). The treaty legally cleared the way for the Centralists to ratify the Constitution of Kresimiria just weeks later. Because Boskenmark had surrendered the territory, the Kresimirian state felt emboldened to implement the draconian Faith Restriction Clause, stripping the newly annexed Pravoslavic population of District X of their voting rights.
Legacy and the “Humiliation of Sinj”
While celebrated in the north as a triumph of Kresimirian sovereignty, the Treaty of Sinj was viewed as a catastrophic betrayal in the south.
For the ethnic Boskens trapped within Kresimiria’s new borders, the treaty proved that Boskenmark had abandoned them to save its own mainland. Refusing to recognize a treaty he had no part in signing, Lev Ruka vanished into the southern hills with his “Black Brigades.” In November 1921, he founded the Bosken Revolutionary Council (BRC-21), plunging Kresimiria into a violent domestic insurgency that would not end until the 1961 Treaty of Brod Moravice.
In Boskenmark, the agreement became known as the “Humiliation of Sinj.” The political fallout from abandoning Moraviskameja discredited the civilian government, fueling a massive wave of right-wing revanchism. This lingering national trauma directly facilitated the rise of General Nielz Metzger and the ultra-nationalist Bosken National Alliance (BNA) in the late 1940s, who won on a promise to eventually tear up the treaty and campaign to regain the lost territories by force.