They foolishly stopped and grouped closely, allowing mortars to easily target them
Unfortunately, when they tried to escape they left the open roads into the fields, where its easy to get stuck in the mud
In spring time, the ground is soft, wet and muddy. Its why the Russian Heavy vehicles were moving on the road, to avoid getting stuck. Its been this way from the start since they picked the wrong time to invade
Intercepted letter couriers show the invasion was to be earlier in the winter when the ground was hard, but it was delayed because of Beijing's Winter Olympics