(Recall the time) when you said to the believers, ‘Does it not suffice you that your Lord should reinforce you with three thousand angels sent down (by Him)? (3:124)

Commentary
NUMBER 3,000: Although as humans, we have been given the freedom to act as we please, however Allah has not created us and simply “left us alone” – there is still the ‘hidden hand’ of Allah which plays a role in the workings of this world.
More often than not, Allah does not interfere with the mechanics of our lives, although He has put various rules in place – such as the fact that when we break His laws, there is an outcome which we may see in this world; and as well, when we do good and follow His ordinances, there is a benefit which we will receive in this current life. The laws of cause and effect govern this world – both at the physical and at the meta-physical level.
At the same time, as we see in the Quran and the lives of the previous prophets and also directly in the life of Prophet Muḥammad, that there are times when Allah directly intervenes and through the assistance of the angels, they have turned the tides on the belligerent opponents of this faith.
We see this in the migration (hijrah) of the Prophet from Mecca to Medina and also in some of the battles which the Muslims were involved in – and none is more clear than the first battle of Badr which the Muslims fought which took place around the 17th of the Month of Ramaḍān in the second year after the migration. 
This was a fierce battle in the history of the Muslims, because up until this point, Allah had prohibited the Muslims from engaging in warfare and so for the Muslims to be victorious and deal a severe blow to the psyche of the polytheists of Mecca and damage their prestige, this was a major turning point in Islam.
Although Allah confirms in another verse that He brought down Angels to aide the Muslims, however we must also realize that as much as this was a physical support for the early Muslim community, we should also look at it as being an emotional backing for the believers and a form of psychological warfare against the enemies.
The fact that the Prophet confirmed to the believers through the verses of the Quran that Allah will come to the aide of the Muslims with unseen Angels was a huge boost in the morale of the believers, and without a doubt, it made them even more enthusiastic to press forth in their mission.
Point of Reflection
The Quran constantly tells the Muslims that we must always prepare ourselves and ensure that we have adequate resources – whether this be human resources, wealth, or anything else so as to protect ourselves and our faith, however, Allah has also promised us that we should do all that we can, and then He will help and support us.