Complex sentence: However, with rare exceptions, all Soviet guns and howitzers at this time were towed rather than self-propelled; this lack of mobility proved to be greatly exacerbated by the absence of roads, the presence of deep snow cover and a scarcity of artillery tractors.
Split into simpler sentences: However, with rare exceptions, all Soviet guns and howitzers at this time were towed rather than self-propelled. This lack of mobility proved to be greatly exacerbated by the absence of roads, the presence of deep snow cover and a scarcity of artillery tractors.