Complex sentence: During what was said to be the worst winter in 30 years, the 1500 men of the 106th held up to of the front, and staying in contact with the XII Corps right flank to its north was difficult because its lines were so thinly spread.
Split into simpler sentences: During what was said to be the worst winter in 30 years, the 1500 men of the 106th held up to of the front. Staying in contact with the XII Corps right flank to its north was difficult because its lines were so thinly spread.