Swarms of military drones have accompanied Royal Marines both above and below the water in the Royal Navy's first test of new combat technology.
Marines tested stealthy reconnaissance drones, heavy-lift resupply models and a self-driving boat.
Officers said "autonomous-advance-force" tests, of how humans and machines could work together, had seen "phenomenal" progress in recent years.
But the use of autonomous technology on the battlefield remains controversial.
"This is a very worrying development in the rush to develop autonomous weapons systems - weapons that once launched, select their own targets and apply violent force," emeritus professor of artificial intelligence and robotics, at University of Sheffield, and co-director of the Responsible Robotics group Noel Sharkey said.
"While drones here were not armed yet, the UK is joining the international arms race with countries like the US, Russia, China, Israel and Australia."
Operating in a "swarm" of six, heavy-duty Malloy TRV150 drones, each capable of carrying up to 68kg (10st 10lb):
- resupplied marines on training "raids" at missile and radar sites in Cumbria and Dorset who had marked their map location on an electronic tablet
- dropped the Remus drone into the sea to "scan the ocean for mines and obstructions", while the Maritime Demonstrator For Operational Experimentation (Madfox) self-driving boat scouted the surface and the Ghost drone - designed, by Anduril, the company built by US technology mogul and Oculus VR founder Palmer Luckey, to be as quiet and difficult to detect as possible - provided a live feed of targets
Another underwater drone, the Raydrive - based on the anatomy of a manta ray - was also being tested, to spy on enemy ships while "almost silent", the Times reported.
The navy said it aimed to "embed autonomous systems on the front line".
The plan was to enhance human capability as part of a "hybrid force", First Sea Lord Adm Sir Tony Radakin said.
"Only by continued experimentation with the latest technology and innovation can we properly prepare our people for the challenges of the future," he said.
Col Chris Haw, who led the tests, said: "We must always remember that this technology is there to enhance commando excellence, not to replace it."
But Prof Sharkey said: "There has been a call to prohibit [autonomous weapons systems that can select and attack their own targets] at the [united nations] UN by thousands of scientists and [artificial-intelligence] AI companies, the director general of the UN, the International Committee of the Red Cross and 31 nation states and 186 [non-governmental organisations] NGOs from around the world.
"The UK has refused to support the ban, saying that they will never use such weapons.
"Yet it looks clearly like they are heading in that direction."