ABC News' Alex Marquardt reports from Aleppo Province:
We spent the last week meeting and staying with families and fighters in the middle of the conflict in Syria.
One evening, we stayed with one unit that was gearing up for what could be the biggest fight of their young lives.
Their faces are not the faces of battle-hardened warriors. They are young men, barely 20 years old. They are defectors from the Syrian military with just basic training.
They call themselves "the martyrs of freedom" and they tell us that they cannot wait to get in the fight. Tonight, they are going to Aleppo, where President Bashar al-Assad said the battle would determine the fate of Syria.
When asked whether they are afraid of going to fight, they respond, "No. No. No. … We're only afraid of Allah."
Allah is their god and their inspiration. What these young men lack in battlefield experience, they make up for with religious fervor and hatred of the Syrian regime.
"The regime has tanks, planes, helicopters. You just have AK-47s and RPGs. How can you defeat them in Aleppo?" they were asked.
"We have Allah with us," said Ali, 21. "He will send soldiers."
This is the holy month of Ramadan, when most Muslims fast all day. After sundown, they break fast. During dinner, the mood is light - not what you'd expect hours before the big fight.
Afterward, it's time to gear up. The young men eagerly wait for their names to be called. Weapons are assigned - AK-47s and rocket-propelled grenades.
If they're nervous, they are hiding it well.
"Victory or martyrdom," Ali says. "God willing."
Ali and the others who have been chosen for battle say goodbye to their brothers-in-arms and head out into the dark. Those left behind are disappointed.
Abdulrahman went last time and tonight, it clearly pains him to be missing out.
For many, this will be the first and maybe last fight of their lives. There is not a hint of doubt among them that this is a battle that must be waged - and won.
ABC News' Enjoli Francis in New York contributed to this story.