Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. The number of megacities – those with populations over 10 million – is expected to jump from 31 today to 60 by 2030. By that time two-thirds of the world’s population is expected to live in urban areas. Fighting in such areas means “we must prepare for a scale of destruction we have only read about in history books,” Gen Townsend said. Future wars will be more Stalingrad than Star Wars, a US General has said as he warns against a relentless focus on technology.General Stephen Townsend, the head of the US Army’s Training and Doctrine Command, told British military leaders at the annual Kermit Roosevelt lecture in London, that combat in an increasingly urbanised world will result in a “scale of devastation beyond our comprehension”.“The future operational environment will be more lethal and on a scale not seen in decades,” he said, as he warned military chiefs that advanced weapons will be of little use in built up areas devastated by fighting.The Kermit Roosevelt lecture series is an annual exchange of speakers from the UK and US militaries. The initiative for the exchanges originated with Mrs Kermit Roosevelt, whose husband – the son of President Theodore Roosevelt – served in both the British Army and US Army across the two World Wars. Kermit Roosevelt died while on active duty in 1943.Modern armies have no idea how to fight in these “hyper populated [and] literally unboundable” areas, Gen Townsend told the audience at the Royal United Services Institute. In the battle to liberate Mosul from Islamic State of Iraq and the Levant (Isil), he had had to ask coalition partners if any army still used flamethrowers, as ‘bunker buster’ bombs had proved useless against fighters dug in amongst destroyed buildings. British Grenadier Guards showing a captured Vehicle-Borne improvised explosive device (VBIED) built by the Islamic State of Iraq and the Levant. After being made safe the vehicle is now being used as a training aid for the Iraqi Security forces. August 8, 2018. Gen Townsend said that buildings taller than about four storeys would just collapse under aerial bombs with the basements and ground floors – where Isil fighters were hiding – largely intact. Subsequent bunker busters just made the ruined structure shake a bit and absorb the blast. He needed a way of killing every last Isil insurgent as they were determined to fight to the death and cause as many casualties as possible.Eventually the Iraqi army deployed a specially designed armoured bulldozer to bury alive the remaining Isil fighters. Soldiers patrolling behind the bulldozer were used to kill any Isil suicide bombers that ran out to stop the vehicle. It was a low-tech and brutal form of war. Gen Townsend questioned whether Western armies had maintained the skills and the stomach for such a fight. “Battles are won by young soldiers fighting in sand, mud, heat and cold,” he said. Tanks and other armoured vehicles will always have utility. Their protection and ability to deliver precise firepower makes them very useful, Mr Barry believes. He points to the so-called ‘Thunder Runs’ in the battle for Baghdad when US forces conducted high-speed raids to test Iraqi defences. Training for such environments is critical, and in this regard the UK has fallen behind, My Barry says. He points to the urban training facilities in Israel, France and Germany as being far superior to the British mock-up town on Salisbury Plain. He says senior army officers are well aware of the relative limitation of the British training facilities and sounds a cautionary note: “armed forces not competent at fighting in urban terrain will increasingly be viewed as incompetent,” he warns. General Townsend, who commanded the coalition effort to defeat Isil from 2016 to March this year, likened the fight to liberate Mosul to Stalingrad, the bloodiest battle of the Second World War. A coalition force of 90,000 soldiers took nine months to finally defeat the 5,000 Isil fighters in Mosul. It took seven days to clear the last pockets of resistance, contained in an area about the size of a premier league football pitch. Ben Barry, Senior Fellow for Land Warfare at the International Institute for Strategic Studies, cautions against “Stalingrad syndrome;” the idea that all urban combat will be similarly destructive. “It’s all to do with the density of the enemy and the degree to which they can stop the attackers movement,” he says.