Overall meaning : Just as Allah entrusted you, Muhammad, with the task of dividing the spoils while some of your companions were averse to the manner you distributed them, so He brought you forth from your home to fight for the truth against the Quraysh idolaters while some of the believers disliked it. They argued with you concerning the truth that Allah had willed (i.e. going forth to battle against the Quraysh idolaters) after it had become manifest (i.e. his informing them that they would be emerge victorious and that there was no escaping the fact they had to fight the enemy). Their condition—due to their intense hatred for fighting when called to it—was like that of someone who was being driven to death with his eyes wide open.
Remember, O believers, when Allah promised you that one of the two parties (the trade caravan or the army) would be yours. You wanted the unarmed party (the caravan) to be yours, but Allah wanted you to fight against the armed party to grant you victory over them, make Islam reign supreme and destroy and wipe out the unbelievers. Thus He would certainly establish the truth firmly by making Islam prevail and prove falsehood, as represented by unbelief and idolatry, to be false even though the evildoing idolaters, who worship others besides Him, hate it.