These brilliant pictures capture the personnel from 21 Engineer Regiment, 4th Battalion, Parachute Regiment, 2nd Battalion the Royal Anglian Regiment and 8 Engineer Brigade.
They took part in exercise Hypogeal Bear on Monday, testing new equipment in the city and below the ground in tunnels.
The challenging operation took place in sweltering heat, as temperatures reached 30C.
It's part of Project Croker, a series of experiments to improve understanding the complexity of operations in cities.
Take a look behind the scenes, courtesy of YEP photographer Bruce Rollinson:
![These brilliant pictures capture the personnel completing a training exercise in Leeds](https://www.yorkshireeveningpost.co.uk/webimg/QVNIMTI2MzY3OTM3.jpg?crop=3:2&width=640)
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These brilliant pictures capture the personnel completing a training exercise in Leeds
![YEP photographer Bruce Rollinson went out with the soldiers on the exercise](https://www.yorkshireeveningpost.co.uk/webimg/QVNIMTI2MzY3OTM4.jpg?crop=3:2&width=640)
![Soldiers from 21 Engineer Regiment, 4th Battalion, Parachute Regiment, 2nd Battalion the Royal Anglian Regiment and 8 Engineer Brigade took part](https://www.yorkshireeveningpost.co.uk/webimg/QVNIMTI2MzY4MTkw.jpg?crop=3:2&width=640)
3.
Soldiers from 21 Engineer Regiment, 4th Battalion, Parachute Regiment, 2nd Battalion the Royal Anglian Regiment and 8 Engineer Brigade took part
![In exercise Hypogeal Bear on Monday, they tested new equipment in the city and below the ground in tunnels](https://www.yorkshireeveningpost.co.uk/webimg/QVNIMTI2MzY4MTkz.jpg?crop=3:2&width=640)
4.
In exercise Hypogeal Bear on Monday, they tested new equipment in the city and below the ground in tunnels
![The challenging operation took place in sweltering heat, as temperatures reached 30C](https://www.yorkshireeveningpost.co.uk/webimg/QVNIMTI2MzY4MjAw.jpg?crop=3:2&width=640)
![It was the hottest day of the year so far](https://www.yorkshireeveningpost.co.uk/webimg/QVNIMTI2MzY4MjAz.jpg?crop=3:2&width=640)