It was a critical and deliberate last-minute deployment on a previously unimportant part of the front. The Russians, having invaded in February 2022, had not anticipated that Ukraine would turn the tables and strike back with the first occupation of Russian territory since the second world war.

Had Moscow known that combat medics were quietly moving into the remote Sumy region, had the message gone up to the Kremlin, Russia might have been better prepared. The medics’ presence would only be required if an outbreak of heavy fighting was anticipated, in an area where none had taken place for over two years.

“We arrived on Monday last week. It had been equipped two days before that,” a surgeon told the Guardian between puffs on a cigarette. It would not be long before the first casualties arrived and days of intense work would begin: Ukraine’s audacious invasion of Russia began the following morning. Their work has been almost round the clock since. “We only get a few hours’ break a day,” another said.

Local civilian authorities, meanwhile, had no idea. Volodymyr Artyukh, the governor of Sumy region, said he found out “same time as you” and instituted an order to evacuate 7,000 people living between 5km and 10km from the border. As for the civilians, though many had seen a military buildup, giving the soldiers potatoes and other vegetables, the first they knew of the reason was when the villages were subjected to intense bombing in the daylight hours after the attack started.