Where did the soldiers gather?
Malbim: It says in Divrei ha'Yamim I, 19:7 that arm camped in Meidva (on the border of Mo'av), and Amon gathered from their cities, in front of this great capitol.
Why did they arrange for war in the opening of the gate?
Malbim: Due to their weakness, they did not want to fight in the field, rather, to take refuge in their fortified city.
Which is "Rechov"?
Radak: It is Aram Rechov. "Aram" written in front of Tzovah refers also to Rechov.
What is "Ma'achah"?
Radak #: It is Aram Ma'achah.
Radak #2: It is Melech Ma'achah.
Why does it say "Levadam"?
Radak: Melech Amon and all of them were inside, and went out to make war. Those hired and mentioned from Aram were in the field; also they would fight Yisrael. When Amon came to fight Yo'av at the gate, Bnei Amon were in front, and Aram was in back, in the field.
Malbim: Due to their weakness, Amon preferred to take refuge in their fortified city. They were far from Aram in the field.
