The Quran

Preface

إِذ أَنتُم بِالعُدوَةِ الدُّنيا وَهُم بِالعُدوَةِ القُصوىٰ وَالرَّكبُ أَسفَلَ مِنكُم ۚ وَلَو تَواعَدتُم لَاختَلَفتُم فِي الميعادِ ۙ وَلٰكِن لِيَقضِيَ اللَّهُ أَمرًا كانَ مَفعولًا لِيَهلِكَ مَن هَلَكَ عَن بَيِّنَةٍ وَيَحيىٰ مَن حَيَّ عَن بَيِّنَةٍ ۗ وَإِنَّ اللَّهَ لَسَميعٌ عَليمٌ

Yusuf Ali

Remember ye were on the hither side of the valley, and they on the farther side, and the caravan¹ on lower ground than ye. Even if ye had made a mutual appointment to meet, ye would certainly have failed in the appointment:² But (thus ye met), that God might accomplish a matter already enacted; that those who died might die after a clear Sign (had been given), and those who lived might live after a Clear Sign (had been given). And verily God is He Who heareth and knoweth (all things).

The little Islamic force from Medīna went out to meet the big Meccan army, and they met on the two sides of a valley at Badr, while the Quraish caravan was on lower ground towards the sea, about 3 miles from Badr.
They were all at cross purposes. The caravan was making for Mecca, but scarcely thought it could get there. The Quraish force was trying to save the caravan and then annihilate the Muslims. The Muslims had decided to let the caravan alone but attack the Quraish army from Mecca, which they thought was going to be small, but which turned out to be big, more than three times their number. Yet the two forces met, precisely at the spot and at the time when a decisive battle should take place and the Muslims dispose of the pretensions of the Meccans. If they had carefully planned a mutual appointment, they could not have carried it out more precisely.
On the Muslim side the few martyrs knew that the victory was theirs and those who survived the battle enjoyed the fruits of the victory. On the pagan side, both those who died and those who lived knew fully the issue joined. Even psychologically both sides went in with full determination to decide the issue.