An army travels on its stomach

An army travels on its stomach
What is the most common meaning of this phrase?

As a non-native English speaker influenced very much by my national idioms I sense three meaning:

1. One must work hardly to get any result.
2. Any progress may be slow.
3. A good soldier is a soldier well fed.

I will be grateful for any comments and explanations.
Thank you.
Valeriy

#3 is correct. It's a quote from Napoleon Bonaparte.