Numbers 2:31

‘All who were numbered of the camp of Dan were a hundred thousand and fifty and seven thousand and six hundred. They shall set forth hindmost by their standards.'

So, on the march they were at the rear of the advance, in order to protect the rear. The powerful tribe of Dan together with Asher and Naphtali consisted of 156 'lph (families/military leaders) and 16 ‘hundreds' (or military units).