By WWI, motor vehicles were common to all nations that fought in the war. Why do you think the Germans (and all armies) were forced to use horses to
move heavy machinery?

Because horses are quiet and strong.

Explanation:

If the were to use a vehicle it would make noise and the opsing team would hear it and break it and horses they would be able to carry it but they are more queit and harder to notice and if the horse its self is seen then most likely thye will mistake them as a animal ecpeacally if its dark outside.

b) the confederacy had to pay all union war expenses.