Otterburn was established in 1911, three years before the First World War made the British Army's gunnery training suddenly and urgently necessary. The site grew with each subsequent conflict. Today it is the United Kingdom's largest firing range, 23 percent of Northumberland National Park, and the only location in the country where the M270 Multiple Launch Rocket System can be fired in training - the weapon's safety footprint requires an eleven-mile by two-mile danger area that no other British range can offer. AS-90 self-propelled artillery also fires here, lobbing 155-millimetre shells across moorland that, on quiet days, looks like a watercolour of the borderlands. The contrast is not lost on anyone who lives near it. The bylaws are clear about the danger; the landscape is clear about its beauty; both are simply true at the same time.

The range exists inside the national park, and the national park exists for the public. Reconciling those two facts requires a system of red flags, signposted danger zones, and a published firing-times schedule that walkers learn to read like a weather forecast. On non-firing days, the byways open: the road through the ranges leading toward Holystone, the path past Otterburn Crossroads, the cattle grids and signposts that tell you, gently, that you are walking somewhere unusual. The MoD's stewardship of the land is, by accident, ecologically valuable. With farming restricted and access limited, parts of the range have become refuges for wildlife that would struggle elsewhere - black grouse, curlew, breeding waders on the wet moor.

Training with live ordnance is dangerous work, and the range remembers its losses. In August 2016, a soldier of the Royal Regiment of Scotland - Conor McPherson, aged twenty-four - was killed at the Heely Dod firing range when a fellow British soldier's round struck him in the back of the head. The Health and Safety Executive issued a Crown Censure to the Army in 2024 over the failures that led to his death. In January of this year, Captain Philip Gilbert Muldowney of the 4th Regiment Royal Artillery was killed during a live-fire training exercise on the ranges. He was a fire support team commander, and the incident is still under investigation. The men who train here understand what the flag means. Sometimes the flag is not enough.

Look down on Otterburn from cruising altitude on a clear day and you see what the cordon protects: a vast openness of heather and rough grassland rolling north toward the Border Ridge, the upper Coquet valley cutting through the hills, the great empty quarter between the Pennines and the Cheviots where almost no one lives. The southern Cheviots include the highest ground here. Artillery fired from the ranges has been clearly heard at Lindisfarne, twenty-five miles to the northeast, and at Fontburn Reservoir to the south. The booms travel. They are part of the soundscape of upper Northumberland, an unwelcome but ordinary feature of weather for anyone who farms or walks within range of the wind.