One in four British soldiers by the next decade won't be human at all.
Chief of the Defense Staff General Sir Nicholas Carter says in the future robots will fight alongside soldiers.
Robots are cheaper in the long run - which will mean a lot less pressure on constrained military budgets.
Carter suggested as many as 30,000 robot soldiers might be fighting alongside soldiers in future conflicts. The British army has a strength of 80,000 officers and men. The entire British Armed Forces has an active duty strength of close to 150,000 personnel.
He said the army will be compelled to include metal warriors in its ranks as it modernizes. These robots won't be humanoid in any way. They will likely be tracked, wheeled or legged machines either toting weapons, sensors or bearing heavy loads.
Carter said an armed forces "designed for the 2030s" might include large numbers of autonomous or remotely controlled machines.
"I suspect we could have an army of 120,000, of which 30,000 might be robots, who knows?" he said.
He explained robots could play a role on battlefields over the next 10 years as part of a "very different" looking army.
"If I projected forward another 10 years, I think we should be in no doubt that warfare will look different, there will be robots on our battlefields in future - there already are today," he said.
The focus on military money, or the lack of it, came into focus following a clash between Prime Minister Boris Johnson and the Chancellor of the Exchequer Rishi Sunak over defense spending.
Johnson wants 15 billion pounds for the army's modernization until 2025 while Sunak suggests a one-year settlement of 1.9 billion pounds. Carter is opposed to the single year package and confirmed he will ask the government for multiyear funding.
"Clearly we're going to argue for something like that because we need long-term investment because long-term investment gives us the opportunity to have confidence in modernization," according to Carter.
He said the military establishment should be amenable to the possibility of building robot soldiers. What the military leadership needs is "to open our minds to perhaps numbers not determining what we should be doing but rather the effect that we can achieve, is really what we should be looking for."
