While France prepares a vast mock war in 2026, the country’s oldest scientific service is quietly mapping shallow waters, measuring currents and feeding data to commanders who need to know, with painful precision, where a landing craft can and cannot go.
France’s giant war game needs a very old brain
ORION 26 is billed as France’s largest military exercise since the end of the Cold War. Up to 12,500 troops, a full carrier strike group, brigades on land, air assets, and even cyber and space units are all plugged into a single storyline: a coalition operation against a fictional expansionist state nicknamed “Mercury”.
The aim is blunt. Paris wants to prove that its forces can be the first to enter a contested theatre and still plug seamlessly into NATO’s command chain. That means testing logistics, decision‑making, interoperability and, less glamorous but absolutely decisive, basic environmental knowledge.
Behind the tanks, helicopters and warships, ORION 26 rests on a dense web of maps, models and measurements produced by specialists most civilians have never heard of.
Those specialists belong to Shom, the French Navy’s Hydrographic and Oceanographic Service. Founded in the early 18th century and turning 305 in 2026, Shom is often described as a “vieux briscard” – a savvy old hand that has survived every regime change by staying useful at sea.
The 305‑year‑old service that tells admirals where to sail
Shom is not a combat unit. It is the national authority responsible for hydrography and oceanography. In peacetime, it surveys the seabed, models tides, tracks currents and produces nautical charts used by both the French Navy and commercial shipping.
In wartime or high‑intensity training, that work becomes strategic. A sandbank in the wrong place, an underestimated swell, or a missing depth measurement can turn an amphibious landing from a neat textbook manoeuvre into a pile‑up of stranded vehicles and damaged hulls.
For ORION 26, planners treated France’s Quiberon Bay, on the Atlantic coast, as poorly known waters. Before sending in three large amphibious assault ships and their landing craft, commanders wanted the equivalent of an MRI scan of the seabed.
DriX Marlin: a robot boat that never sleeps
To get that scan, Shom deployed one of its newest tools: the DriX‑H8 “Marlin”, an unmanned surface vessel that looks like a sleek red kayak bristling with antennas and sensors.
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During ORION 26, DriX Marlin carried out its first fully autonomous mission in support of a major exercise. It operated in Quiberon Bay, over the horizon from Brest, by day and by night, under a navigation certificate issued by the French Navy.
For three days straight, in choppy seas, the drone performed continuous hydrographic surveying. Crew in the Atlantic Hydrographic and Oceanographic Group’s command centre piloted and monitored it remotely, coordinating with the crewed survey ship La Pérouse.
The mission showed that France can collect high‑quality seabed data quickly, without putting a crew at risk and with far greater endurance than a manned launch.
Shom officials stress that DriX is not a tech toy for showy demonstrations. It is part of a broader shift toward distributed, robotic sensing at sea, cutting the time between “we need data” and “here are the charts” from weeks to days.
Missions in the shadows to secure the landings
In the ORION 26 scenario, Quiberon Bay is a potential beachhead. Before amphibious task groups move in, Shom’s teams must remove as much uncertainty as possible.
Their objectives included:
- high‑resolution mapping of the seabed along likely approach routes,
- identifying hazards such as rocks, wrecks or sandbars,
- refining bathymetry data (depth and seabed shape),
- updating the information commanders use for ship handling and landing craft operations.
Once field measurements were complete, Shom technicians processed the data at speed and generated updated products for amphibious group commanders. Instead of relying on older charts or generic depth estimates, captains could plan their runs to the beach with fresh figures.
The invisible battle: charts, models and timing the surf
Shom’s role in ORION 26 did not stop at sounding the seabed. Its experts also supplied what the French military calls “environmental support” to the joint headquarters.
At the request of the French maritime component (FRSTRIKEFOR) and the Atlantic command, Shom produced a suite of specialised maps, including:
- combined land‑sea command charts for planning across the shoreline,
- aeronautical information charts for aircrews flying over coastal zones,
- Amphibious Operations Graphics (AOGs) detailing landing sites and beach characteristics.
Alongside the cartographers, PREVOPS teams, who specialise in operational oceanographic forecasting, built around ten high‑resolution numerical models for each potential landing area. They did this in about two weeks, a tight schedule for such complex simulations.
Those models took into account currents, tides, wind, wave conditions and detailed bathymetry. The goal was to predict the state of the sea at the exact time of a planned landing, not just “morning” or “afternoon”.
For an amphibious commander, the difference between green light and postponement often comes down to what the last 200 metres of surf will look like.
During the intense phase of ORION 26, forecasts were updated daily, seven days a week, then pushed to amphibious assault ships so that bridge teams and landing force commanders could adjust timing and routes.
Inside Shom: people, ships and robots
Behind these models sits a relatively small but specialised workforce and a growing fleet of smart platforms.
| Category | Main details |
| Staff | Roughly 500–530 personnel, a mix of civilians and military: hydrographers, oceanographers, engineers, sailors and technicians, based in Brest, Toulouse, the Paris region and overseas territories. |
| Naval assets | Dedicated survey ships such as Beautemps‑Beaupré, Borda, La Pérouse and Laplace, plus coastal launches and offshore vessels, with modern replacements planned from 2028. |
| Drones | Underwater gliders like SeaExplorer with months‑long endurance, smaller micro‑AUVs such as NemoSens for close‑in inspection, and DriX surface drones for rapid coastal hydrography. |
| Budget and data | An annual budget in the €55–60 million range and national portals providing bathymetry, tide gauges and current data for both defence and civilian users. |
Why data now shapes modern amphibious warfare
Modern amphibious operations are sometimes imagined as a cinematic rush to the beach under fire. In reality, they are carefully choreographed logistical projects where physics can hurt more than bullets.
Landing craft need certain depths along the approach and at the beaching point. Heavy armour has strict limits on slope and soil bearing capacity. Helicopter pilots care about sea spray, gusts and turbulence close to the waterline.
Shom’s contribution sits exactly at that intersection of physics and planning. Its models help answer questions such as:
- Will a 30‑ton vehicle bog down in this stretch of sand at low tide?
- Can a landing craft reverse off the beach if the swell builds unexpectedly?
- Is there a hidden channel that could be used as a safe lane for smaller boats?
For ORION 26, French planners can also test what happens when data is missing. Part of the exercise is about operating under uncertainty: what if a key sensor fails, a drone is jammed, or a satellite feed is cut at a bad moment?
From training scenario to real‑world crises
Although ORION 26 is fictional, the scenarios echo real‑world crises. In any future operation—evacuating civilians from a collapsing state, reinforcing a Baltic ally, or responding to a major coastal disaster—the first question is often “what do we know about this coastline?”
If a cyclone has rearranged sandbanks or if the last detailed survey dates from the 1970s, commanders face nasty surprises. Robotic survey assets like DriX and nimble modelling teams allow Shom to update that picture in days, giving political leaders more options.
There are risks too. Increased reliance on digital models and data links means adversaries can target those systems with cyberattacks or electronic warfare. ORION 26 provides a testbed for such scenarios: what if GPS is spoofed, or tidal data is manipulated? Training through those edge cases now reduces the shock in real operations.
Key terms the exercise brings into focus
Several technical notions underpin ORION 26’s “invisible” side:
- Bathymetry: the underwater equivalent of topography, describing the shape and depth of the seabed. Accurate bathymetry prevents groundings and optimises routes.
- Hydrography: the science of measuring and describing physical features of oceans, seas and coastal areas for navigation and operations.
- Operational oceanography: real‑time or near‑real‑time monitoring and modelling of the sea to support practical decisions, from naval manoeuvres to search‑and‑rescue.
- Amphibious Operations Graphics (AOGs): specialised charts that integrate depth, tides, surf, beach gradients and obstacles, tailored for landing force planners.
In ORION 26, these once‑esoteric tools step onto centre stage, even if they remain largely unseen. Long before the first mock shot is fired, a 305‑year‑old service has already shaped what is possible, where ships can sail, and how safely troops can reach the shore.