This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

For months each side had been building forward rifle pits and defensive positions, which resulted in many skirmishes. Artillery fire aiming to gain superiority over the enemy guns.:450462 September saw the final assault. On 5 September, another French bombardment (the sixth) was followed by an assault by the French Army on 8 September resulting in the capture of the Malakoff by the French, and following their failure to retake it, the collapse of the Russian defences. Meanwhile, the British captured the Great Redan, just south of the city of Sevastopol. The Russians retreated to the north, blowing up their magazines and the city fell on 9 September 1855 after a 337-day-long siege.:106
What was being built that caused unpremeditated fighting on each side?