Then you travel in the land peacefully for 4 months, and you know that, indeed, you are not going to defeat Lord Allah; indeed, Allah will disgrace the disbelievers.
As told in verse 8: 58, if you happen to see a people breaching the agreements with you, then you throwback it to them on equal terms by saying: “We have no further responsibility with you”. Without declaring the disagreement openly with such people, starting a battle is prohibited for the believers. But when the disbelievers at the time of Messenger started to breach the agreements secretly and made treaties with the Jews and hypocrites against the believers, this verse was revealed. The 4 months mentioned in this verse was from Dul-Hajj 10th of Hijra 9 to Rabbiyul-Akhir 10th of Hijra 10.
During Messenger’s period, the Lord’s Book was not codified. But Mecca Mushriks were called as the Kafirs since the verses of Lord’s Book was revealed in their language. But after 30 years of Messenger’s departure, the Book reading hypocrites and their Mushrik followers are the true disbelievers and Fujjar as explained in 4: 150-151. So, they will be dragged prone on their faces into Hell, such are the most strayed and they are in the worst place as explained in verses 2: 6-7 and 18. See explanation 2: 85; 4: 91 and 6: 25-26.