The evolving battle for Bakhmut: casualties, tactics, and Ukraine's refusal to retreat.

The battle for Bakhmut, a city in Ukraine's eastern Donbas region, has been raging for over seven months, making it the longest battle of the war so far. Two Ukrainian army brigades defending the city's southern flank gave the BBC access to their positions last week as fierce fighting continued in and around Bakhmut. Troops say Russian casualties far outweigh theirs, but the enemy is deploying new techniques to try to seize the city and surrounding countryside.