The Uskoks were Christian refugees who transformed into maritime raiders operating on behalf of the Habsburg Empire, though often only loosely controlled by it. While they certainly were pirates in the classic sense, they were also strategic actors in an early modern proxy conflict between the Habsburgs and the Ottoman and Venetian Empires.
Building on this role, the Uskoks functioned as a de facto proxy, with the Habsburgs exploiting them to pressure their strategic competitors without committing imperial forces or provoking open war. This relationship manifested through Habsburg provision of sanctuary, stipends, and political protection, which enabled Uskok operations while preserving plausible deniability for Vienna. In return, Uskok piracy disrupted Ottoman coastal trade, tied down enemy resources, and complicated Venetian-Ottoman diplomacy in ways advantageous to Habsburg strategic aims.
The Uskoks’ irregular operations on the Adriatic Sea and their relationship with the Habsburgs serve as a compelling historical analogue to contemporary proxy warfare and demonstrate the risks that accompany such relationships. Over time, Uskok autonomy, predatory behavior toward neutral shipping, and periodic escalation threatened to draw the Habsburgs into conflicts they did not intend to fight. Through this lens, the Adriatic coastline of the 16th and 17th centuries emerges as an instructive stage for understanding enduring patterns of asymmetry, deniability, and resistance. By juxtaposing the Uskok experience with modern irregular warfare doctrine, insights emerge into the strategic use and inherent dangers of proxy dynamics.
Background
In the early 17th century, the Uskoks settled along the jagged eastern Adriatic coast of present-day Croatia after fleeing Ottoman advances in Bosnia, Herzegovina, northern Albania, and the Dalmatian hinterland. Most were not seafarers by origin; they were pastoral communities accustomed to guerrilla-style defense in rugged terrain. After their relocation to Senj (modern-day Croatia) under Habsburg protection, geography reshaped their future.
Perched atop a rocky bluff over the northern Adriatic with limited arable land, Senj forced the Uskoks to adapt. They learned small-craft seamanship and coastal raiding out of necessity, improvisation, and interaction with local Croatian mariners already proficient in navigating the narrow channels and inlets of the Velebit coast. Over time, their land-based irregular tactics blended with acquired maritime skills, creating a hybrid force uniquely suited to hit-and-run attacks against Ottoman and Venetian shipping.
The Habsburgs, perennially short on forces and funds, recognized the value of the capability the Uskoks presented. What began as a defensive refugee settlement evolved into a launchpad for raids, smuggling, and paramilitary activity. Initially tasked with defending the landward frontier, the Uskoks adapted to maritime operations and sustained themselves through ship-borne raiding. This transition emerged organically, aided by local Croatian mariners who provided the small craft and coastal expertise needed for fast, covert operations.
Although the Habsburgs did not formally direct them to become sea raiders, imperial officials quietly tolerated attacks on Ottoman shipping because the Uskoks’ actions had strategic value. Uskok raids were effective in disrupting Venetian and Ottoman military and commercial flows at minimal cost to Vienna. By harassing Ottoman supply lines, complicating Venetian–Ottoman cooperation, and diverting enemy attention toward coastal defense, the Uskoks created pressure points that the resource-strapped Habsburgs could not achieve with regular forces. Even when Uskok depredations expanded to include lucrative Venetian targets, Habsburg diplomats publicly condemned the violence while privately recognizing the strategic dilemmas it imposed on rival powers.
The Uskoks’ rise unfolded amid a tense and fragmented geopolitical landscape. In the early 1600s, the Adriatic was a contested and weakly governed maritime arena where the ambitions of Venice, the Ottoman Empire, and the Habsburgs collided. With no power able to impose consistent authority across a fragmented coastline, the region functioned as a maritime gray space. The Uskoks thrived in these seams between empires: striking Ottoman supply vessels moving between Balkan ports, ambushing Venetian merchant convoys, and exploiting the inability of large Ottoman and Venetian fleets to effectively police the labyrinth of inlets; the Uskoks used this maze of maritime waterways to their advantage, blending in with coastal communities who shared shared language, faith, and kinship ties with the Uskoks. Though the Habsburgs lacked the naval capacity to control the sea themselves, Uskok raids allowed them to apply pressure across the maritime corridor, making these irregular fighters an outsized factor in the struggle for influence in the Adriatic.
Unconventional Warfare in the Uskok Campaign
The Uskoks fully demonstrated underground networks, auxiliaries, and guerrilla tactics conducted in denied areas, attributes of uncoventional warfare.
Underground. The Uskoks relied on a dispersed clandestine infrastructure built from kinship ties, shared faith, and refugee networks along the Dalmatian coast. These underground elements provided intelligence on Ottoman and Venetian ship movements, facilitated communications and resupply, and offered concealment within sympathetic coastal settlements. This informal but resilient system enabled the Uskoks to operate with persistence in zones where rival powers claimed authority but struggled to assert control.
Auxiliary. Beyond their core fighters, the Uskoks drew support from a broad auxiliary population of local fishermen, boat owners, frontier militias, and traders. These part-time enablers offered transportation, logistics, guides, and early warning, extending Uskok reach far beyond Senj. Their decentralized contribution mirrors the auxiliary role in unconventional warfare doctrine, where local supporters expand operational depth without being part of the guerrilla force.
Guerrilla Force. The Uskoks themselves functioned as a maritime guerrilla element, conducting hit-and-run attacks against Ottoman supply lines and Venetian merchant traffic. They leveraged fast boats, intimate coastal knowledge, and avoidance of decisive engagement to erode adversary freedom of action. Their asymmetric tactics, use of surprise, and rapid dispersal into inlets and coves reflect well-understood principles of guerrilla warfare adapted to the maritime domain.
Area Complex. Operating along a fragmented and weakly governed coastline, the Uskoks took advantage of a natural “area complex”—a mosaic of islands, inlets, coves, and sympathetic communities that provided depth, mobility, and concealment. This complex terrain allowed them to survive inside what would today be considered contested or semi-denied maritime zones. Their ability to exploit this environment illustrates how irregular actors maneuver within gaps in state control to sustain operations against stronger adversaries.
Uskoks as Proxy Actors: Strategic Utility and Risk
The Habsburgs’ relationship with the Uskoks was defined by pursuit of self-interest. They armed and supplied the fighters of Senj, offered protection from reprisals, and tolerated their activity as long as it was directed at the right targets. Yet they also denied official complicity when complaints poured in from Venice, or when raids disrupted their diplomatic efforts.
Proxy in Action – Raid on Venetian shipping near Pago
An illustrative example of an Uskok engagement that served Habsburg interests was the series of raids on Venetian shipping near the island of Pago (Pag in present day Croatia) in 1615, which became the immediate catalyst for the broader Uskok War (1615–1618) between Venice and the Habsburg Monarchy.
For years, tensions between Venice and the Habsburgs had simmered over competing territorial claims and influence along the Adriatic coast. Uskok attacks had become a chronic irritant that came to a climax in the Pago raids, when the Uskoks not only captured multiple Venetian vessels but also attacked them in waters Venice considered firmly within its maritime jurisdiction. The violence was unusually public and brazen, with Venetian crews killed or imprisoned, and the captured goods sold openly in markets aligned with the Habsburgs.
These actions were viewed in Venice not as isolated piracy but as a direct challenge to Venetian sovereignty and prestige. The loss of ships near Pago struck at a critical segment of Venetian trade routes linking the northern Adriatic to Dalmatian ports. It also suggested to the Venetian Senate that the Habsburgs were either unwilling or unable to restrain their proxy, presenting an unacceptable situation in a region where commercial security underpinned political power.
As a result, Venice responded far more aggressively than in prior incidents. The Senate denounced the Habsburgs and mobilized naval forces to suppress the Uskoks and pressure their patrons. Although the Habsburgs denied directing the raids, they were reluctant to dismantle their proxy. The Pago raids, therefore, served as a tipping point: Uskok piracy, once a tacitly tolerated tool of indirect pressure, escalated into a strategic confrontation neither Venice nor the Habsburgs could ignore.
Lessons for Contemporary Proxy Warfare
The Uskoks offered a low-cost but strategically useful tool for shaping the balance of power in the Adriatic. As a proxy force, they provided the Habsburgs with an inexpensive means of pressuring the Ottoman Empire along its vulnerable maritime flank. By raiding Ottoman supply vessels, coastal garrisons, and small trading craft, the Uskoks forced the Ottomans to allocate troops and patrol ships to defend routes that previously required little oversight.
These small but persistent attacks strained Ottoman logistics in Dalmatia, unsettled coastal populations loyal to Istanbul, and signaled Habsburg willingness to contest Ottoman influence without committing regular forces. Because the Uskoks operated beyond formal imperial command, Vienna could leverage their aggression as a deniable form of resistance while avoiding a direct naval confrontation with the far stronger Ottoman fleet. In this way, the Uskoks functioned as a pressure tool that allowed the Habsburgs to impose costs on their rival at minimal strategic risk and expense.
Uskok raids also disrupted Venetian commerce, eroding the economic foundation of Venice’s maritime dominance and forcing the republic to divert ships and soldiers to coastal defense. These attacks also inflamed political tensions within Venice, as merchant guilds and shipowners demanded protection and retaliation. Crucially, the Uskoks provided the Habsburgs with a deniable means of exerting pressure: they could quietly benefit from the strain the Uskoks imposed on their rivals while publicly disavowing direct responsibility. As a result, the Uskoks became an asymmetric lever that allowed a resource-constrained Habsburg monarchy to influence regional power dynamics without committing major forces.
This dynamic sat at the heart of what Andrew Mumford terms a “sponsored” proxy relationship; that is, one in which the sponsor supports but does not fully control the proxy. The advantages were obvious: the Uskoks kept Ottoman garrisons on edge and complicated Venetian trade routes without drawing the Habsburgs into open war. The political risks and actual costs were also high. As Uskok depredations escalated, Venetian retaliation forced the Habsburgs into a conflict they had not sought, culminating in the Uskok War.
U.S. Army publications such as ATP 3-05.1 and ADP 3-05 emphasize that resistance partners inevitably pursue their own objectives and that a sponsor’s ability to direct or restrain them is limited to influence, not command. The Habsburg experience with the Uskoks reflects this pattern clearly. What appeared to be a low-cost asset when interests aligned could rapidly transform into a liability when Uskok actions exceeded what Vienna could shape or contain. Their value as an irregular partner was real but unstable, illustrating the enduring challenge sponsors face when the behavior of a semi-autonomous proxy generates strategic costs for the state that enabled it.
When Uskok attacks provoked retaliation from Venice, the Habsburgs were forced into a conventional war (Uskok War of 1615–18) that they had sought to avoid with irregular operations. This war resulted in the Treaty of Madrid (1617), which reset the regional balance of power at status quo ante with no real benefit to Austrian Habsburgs but also had one practical negative outcome: the destruction of the Uskoks as a proxy force. The strategic lesson was clear: the Uskoks offered short-term tactical benefits when their activity aligned with Habsburg interests, but their limited ability to restrain the Uskoks ultimately produced larger strategic setbacks when Venice imposed consequences on the sponsor rather than the proxy.
Conclusion
The Uskoks’ example shows that even centuries ago, states were willing to trust irregular actors to shape conditions, exert influence, avoid attribution, and challenge adversaries in places where direct intervention would be too costly or risky. Historically as well as today, that trust of a non-state proxy to advance strategic objectives against other state competitors has both potential and perils that must be understood as part of the decision to employ them.
Similar to contemporary insurgents and militias, the Uskoks operated in politically sensitive spaces and drew strength from hybrid identities that blended refugee status, frontier soldiering, and religious militancy. Many were displaced Croats, Serbs, and other Slavs who simultaneously saw themselves as subjects of the Habsburg monarchy, defenders of Christendom, and avengers of Ottoman encroachment. This layered identity allowed them to justify raids as both survival and holy duty. They also leveraged local grievances, such as heavy Ottoman taxation, forced conversions, and frontier violence, into operational support from coastal Christian communities that viewed them as protectors rather than pirates. Their legitimacy rested less on formal sponsorship than on solidarity with populations who shared their faith and trauma; villages provided shelter, intelligence, and recruits not because of Habsburg direction, but because the Uskoks symbolized resistance to Ottoman domination. This social foundation gave the Uskoks the freedom of movement and local support that sustained their operations far more effectively than traditional material resources alone.
The Habsburg experience also reinforces a lesson often ignored: proxies are not precision tools. They have their own agendas, and their loyalty is contingent on opportunism and continued political or materiel support. The Uskoks may have served Habsburg interests for a time, but when their actions outpaced imperial intent, they dragged their patrons into a broader conflict. The war ultimately returned the Habsburgs to their pre-Uskok position of strategic leverage (without any notable gains) highlighting the limits of relying on a semi-controlled proxy.
The Uskoks, on the other hand, were forced by the Venetians to resettle deep into the interior after the war, effectively dismantling the group as a maritime force. Venice, meanwhile, achieved its primary objective of restoring security to its Adriatic trade lanes. Contemporary sources highlight that the war produced high losses and only modest military gains for Venice. In strategic terms, the Habsburgs gained little, with their irregular auxiliaries offering some short-term leverage, but their inability to restrain Uskok operations ultimately exposed the Habsburgs to Venetian retaliation and international pressure. With the proxy force dismantled and no territorial or political gains secured, the war demonstrated an often-observed outcome of a sponsor-proxy relationship: the immediate operational benefits the Uskoks provided were outweighed by larger strategic, diplomatic, and economic costs to their Habsburg patrons.
The Uskok episode offers a durable reminder that proxy forces can generate strategic opportunity but are equally capable of becoming a strategic liability. For modern practitioners and analysts alike, the Adriatic of the early seventeenth century illustrates that the true cost of a proxy is often paid not on the battlefield, but in the diplomatic, political, and economic consequences that follow.
Dr. Robert Redding (Colonel, ret. US Army) is a national security practitioner with global experience in security cooperation and diplomacy. His military service included operational assignments in conventional and special operations units as well as at the US embassies in Tel Aviv and Ljubljana.
Main Image: Joadl. Uskok Ships Chasing a Large Ship, photograph, 27 July 2009. Wikimedia Commons. Accessed Nov 9, 2025. https://commons.wikimedia.org/wiki/File:Uskoken_im_Senjer_Kanal.JPG
The views expressed are those of the author and do not reflect the official position of the Irregular Warfare Initiative, Princeton University’s Empirical Studies of Conflict Project, the Modern War Institute at West Point, or the United States Government.
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