The 93rd MP Battalion and Coastal Interdiction in Vietnam
The 93rd Military Police Battalion formed part of the American military police presence in Vietnam during a war shaped by roads, rivers, ports and coastlines. Its story belongs to the wider effort to protect bases, regulate movement, secure military cargo and help prevent enemy personnel or supplies from passing through the Republic of Vietnam’s transport network.
“Coastal interdiction” can sound like a naval mission, and much of the offshore work was carried out by the U.S. Navy and Coast Guard. Army military police contributed from the shore: guarding port facilities, checking vehicles and documents, supporting customs controls, escorting convoys and responding to incidents around installations and transport hubs. For Australian readers familiar with the role of the Australian Army Provost Corps, the closest comparison is a military policing task expanded across a difficult and dangerous theatre.
The Battalion Within The Military Police Structure
The 93rd Military Police Battalion served under the 18th Military Police Brigade, the major U.S. Army military police headquarters in Vietnam. The brigade coordinated a range of duties, including law enforcement, prisoner operations, traffic control, security missions and support for the many American installations spread across the country.
A battalion headquarters did not operate as a single patrol unit in the modern sense. Its companies and detachments could be assigned to different locations and duties, sometimes far apart. That arrangement reflected the geography of the war. A port on the coast, a large logistics base inland and a convoy route between them could all require military police support at the same time.
The 93rd’s work therefore sat between conventional security and civil administration. MPs enforced military regulations, maintained order around bases and dealt with soldiers and civilians, while also operating in areas where the distinction between a secure rear zone and an active combat environment was often unreliable.
Why The Coast Mattered
Vietnam’s coastline and waterways were essential to the American war effort. Equipment, fuel, food, ammunition and replacement vehicles arrived through ports before moving to depots, airfields and combat units. Coastal roads connected major military areas, while rivers and canals offered routes for both legitimate commerce and clandestine movement.
The enemy did not need to defeat a port in a conventional assault to disrupt operations. A mine, sabotage attempt, ambush, stolen vehicle or forged identity document could delay supplies and expose weaknesses in the system. Interdiction was consequently a layered task involving observation, inspection, intelligence, patrols and rapid response rather than a single type of operation.
The Navy’s Market Time campaign and related river and coastal patrols addressed movement on the water. Army units protected the facilities that made those patrols possible and helped control what moved through land-side gates. Military police were especially relevant where shipping, vehicles, warehouses, personnel and paperwork converged.
The Military Police Contribution
At a coastal installation, military police could control entry points, inspect passes, regulate traffic and protect sensitive areas. They might check a truck against its manifest, investigate a discrepancy in cargo or escort a convoy leaving the port. These apparently routine duties had operational consequences because an unverified vehicle or unauthorised person could carry explosives, weapons or information.
Port security also involved close attention to local conditions. Vietnamese workers, contractors, drivers and traders were part of the daily life of many installations. MPs had to distinguish ordinary activity from suspicious behaviour without turning every encounter into a confrontation. Language barriers, incomplete intelligence and pressure to keep supplies moving made judgement central to the job.
The duties could become violent without warning. Military police carried weapons and operated under threat from mines, snipers, ambushes and attacks on fixed positions. A guard post, checkpoint or convoy route could be targeted precisely because it was predictable. The policing function remained visible, but the surrounding conditions were those of an insurgency and a conventional war combined.
Roads, Convoys And The Maritime Supply Chain
The coastal mission did not stop at the shoreline. Once cargo was unloaded, it had to travel by truck, rail, barge or aircraft. Convoy security linked the port to storage areas and forward locations, making traffic control a practical form of force protection. MPs could regulate departure times, organise vehicle movement and respond to accidents or attacks.
The long Vietnamese road network presented its own hazards. Bridges, culverts and narrow routes created natural points of vulnerability. Weather could turn an unsealed road into mud, while congestion around a base made vehicles easier to observe and target. A convoy that arrived safely still depended on secure loading areas, reliable drivers and controlled access at its destination.
This is one reason a simple label such as “coastal interdiction” can obscure the full picture. The mission involved a chain of connected activities: seaward surveillance, port protection, cargo handling, documentation, traffic management and movement along inland routes. The 93rd MP Battalion’s relevance lay in that network of security tasks rather than in a claim that Army MPs replaced naval patrol forces.
Tet And The Pressure On Rear Areas
The Tet Offensive in 1968 demonstrated how vulnerable supposedly secure areas could be. Attacks and attempted attacks struck urban centres, military installations and government sites across South Vietnam. The American Embassy in Saigon became a powerful symbol of the failure of assumptions about rear-area security, even though the wider offensive was ultimately repelled.
Military police were among the personnel required to restore order, protect key facilities and manage movement during the crisis. Their responsibilities could expand rapidly from routine gate duty to emergency reaction, traffic control, prisoner handling and support for commanders trying to understand a confused situation. Reflections by MPs after Tet often reveal how quickly a familiar security environment could change.
For an independent historical tribute, photographs and recollections are valuable but should be read with care. A caption may identify a place without explaining the wider operation; a veteran’s memory may preserve the emotional reality of an event without providing a complete unit chronology. Comparing personal accounts with official histories, morning reports, maps and award records gives a more balanced view of the battalion’s service.
Australian audiences may recognise this way of remembering service through RSL archives, unit associations and oral-history projects. A photograph held by a family in Brisbane or Melbourne can carry details absent from a formal war diary, while a Canberra memorial record may provide the dates and service information needed to place it accurately. Both forms of evidence matter.
Remembering The Mission
The people who performed these duties were not all doing the same job, and their experiences varied by company, location and period. A soldier assigned to a gate, a convoy escort, a port facility or a headquarters could encounter different levels of danger. The battalion’s history is strongest when it preserves those distinctions rather than presenting every task as identical.
The term “MP” can also mislead modern readers. In Vietnam, military police were law-enforcement professionals, traffic controllers, guards, investigators and combat soldiers depending on the circumstances. Their work supported combat formations while also maintaining the rules and systems required by a large overseas military presence.
The 93rd MP Battalion and the Coastal Interdiction Mission are therefore best understood through connections: between ship and road, port and depot, paperwork and security, routine policing and sudden combat. This perspective honours the battalion without overstating its role. It also places individual photographs and memories within the operational world that gave them meaning.
For Australians, the subject has a regional dimension. Vietnam was part of Australia’s own military history, with Australian forces operating at places including Nui Dat, Vung Tau and Saigon. The language of “the regimental family,” an RSL gathering or a Vietnam Veterans Day service on 18 August can make an American unit’s story feel less distant, while still respecting the differences between the two countries’ forces and missions.
| Mission area | Typical military police contribution | Wider security connection |
|---|---|---|
| Port and installation security | Gate control, guard duty, access checks and incident response | Protected unloading areas, warehouses and personnel |
| Cargo and customs control | Documentation checks, vehicle inspection and investigation of irregularities | Reduced the risk of sabotage, theft and unauthorised movement |
| Convoy movement | Traffic regulation, escort support and response to breakdowns or attacks | Linked coastal facilities with inland depots and bases |
| Waterway and coastal operations | Shore-side security and coordination around transport facilities | Complemented naval and Coast Guard patrols rather than replacing them |
| Emergency operations | Crowd control, route control, prisoner handling and reinforcement of threatened sites | Helped maintain command and movement during attacks such as Tet |
The surviving record cannot answer every question about the 93rd. Some operational details remain scattered across unit documents, veterans’ accounts, photographs and official collections. That incompleteness is part of the archival challenge, especially for a project independent of the U.S. Army and Department of Defense.
What can be established is the importance of the battalion’s supporting role. By securing people, places, vehicles and procedures, military police helped keep a huge logistics system functioning in a war where the rear was never entirely safe. Their coastal and transport duties were less visible than a major battle, yet they shaped whether troops and supplies could move through Vietnam at all.
