John Gill Commentary Nehemiah 4:13

"Therefore set I in the lowest parts of the space behind the wall, in the open places, I set [there] the people after their families with their swords, their spears, and their bows." — Nehemiah 4:13 (ASV)

Therefore set I in the lower places behind the wall
Where the wall was lowest, and the enemy could more easily break it down, or get over it:

and on the higher places ;
where the wall was higher; or rather on the towers upon the walls, as the word signifies the tops of rocks, which are dry and smooth, see (Ezekiel 24:2Ezekiel 24:8) .

I even set the people after their families ;
according to their rank, number, strength, and valour:

with their swords, their spears, and their bows ;
with weapons they could use both near, and at a distance.