Military Strategy in Islam

قَدْ كَانَ لَكُمْ ءَايَةٌ فِى فِئَتَيْنِ ٱلْتَقَتَا ۖ فِئَةٌ تُقَـٰتِلُ فِى سَبِيلِ ٱللَّهِ وَأُخْرَىٰ كَافِرَةٌ يَرَوْنَهُم مِّثْلَيْهِمْ رَأْىَ ٱلْعَيْنِ ۚ وَٱللَّهُ يُؤَيِّدُ بِنَصْرِهِۦ مَن يَشَآءُ ۗ إِنَّ فِى ذَٰلِكَ لَعِبْرَةً لِّأُو۟لِى ٱلْأَبْصَـٰرِ

Already there has been for you a sign in the two armies which met [in combat at Badr] - one fighting in the cause of Allāh and another of disbelievers. They saw them [to be] twice their [own] number by [their] eyesight. But Allāh supports with His victory whom He wills. Indeed in that is a lesson for those of vision.

إِذْ يُرِيكَهُمُ ٱللَّهُ فِى مَنَامِكَ قَلِيلًا ۖ وَلَوْ أَرَىٰكَهُمْ كَثِيرًا لَّفَشِلْتُمْ وَلَتَنَـٰزَعْتُمْ فِى ٱلْأَمْرِ وَلَـٰكِنَّ ٱللَّهَ سَلَّمَ ۗ إِنَّهُۥ عَلِيمٌۢ بِذَاتِ ٱلصُّدُورِ

[Remember, O Muḥammad], when Allāh showed them to you in your dream as few; and if He had shown them to you as many, you [believers] would have lost courage and would have disputed in the matter [of whether to fight], but Allāh saved [you from that]. Indeed, He is Knowing of that within the breasts.