They reached a crossroads in the forest, at which they had to turn in loose sand and struggle up a slope. The wheels of the gun carriages sank in the sand and the horses, as exhausted and undernourished as the men, could not budge them, nor did the exertions of the gun crews help. Yaroslav led his men to the aid of the cheerful, bullet-headed sergeant major, and they got two of the guns moving, but the sergeant major had to harness eight horses instead of six to each of the others, and the whole column was held up yet again.
Source: wiktionary