Did Muhammad actively massacre the Quraishi Army POW’s at Badr?
The battle at Badr ensued only after Muslims suffered persecution and murder for 13 years in Mecca, left their belongings and migrated peacefully to Medina, and then were pursued by Meccans who intended to kill them [the Muslims]. As a final resort, Muslims took up the sword—often wooden—to defend their right to religious freedom. At a place called Badr, near Medina, some 300 ill-trained and ill-equipped Muslims with two horses overcame a well-trained well-equipped army of 1,000 Meccan soldiers and 100 horses. In total, 14 Muslims and 70 Meccans were killed in Badr, and 70 Meccans were taken captive. Critics’ claims that the Muslims mistreated and even killed the Meccan POWs is patently false—history records the exact opposite. Here, we present the candid testimony of Sir William Muir to demonstrate accordingly:
The Refugees had houses of their own, received the prisoners with kindness and consideration. ‘Blessings on the men of Medina!’ said one of these in later days: ‘they made us ride, while they themselves walked afoot; they gave us wheaten bread to eat when there was little of it, contenting themselves with dates.’ It is not surprising, therefore, that some of the captives, yielding to these influences, declared themselves Believers, and to such their liberty was at once granted. The rest were kept for ransom. But it was long before Koreish could humble themselves to visit Medina for the purpose. The kindly treatment was thus prolonged, and left a favourable impression on the minds even of those who did not at once go over to Islam. Eventually the army of Badr was enriched by the large payments given. The captives were redeemed according to their several means some paying a thousand, and others as much as four thousand pieces. Such as had nothing to give were liberated without payment; but a service was required which shows how far Mecca was in advance of Medina in learning. To each were allotted ten boys, to be taught the art of writing; and the teaching was accepted as a ransom. 
The captives could not help but testify that their captors treated them better than they treated themselves. At a time in Arabia when POWs were either put to death or enslaved, these POWs were allowed to purchase their freedom. Those who could not purchase their freedom “suffered” the responsibility of teaching ten children how to read. Education was their ransom. No example in history can even compare to this high standard Prophet Muhammad demanded of the Muslims.
The following Qur’anic verse is cited by critics to support their allegations: “It does not behoove a Prophet that he should have captives until he engages in regular fighting in the land. You desire the goods of the world, while Allah desires for you the Hereafter. And Allah is Mighty, Wise.” 
Contrary to interpretation that this verse requires Muslims to kill captives, this verse in fact condemns keeping captives at all unless it is during wartime. As mentioned earlier, the Qur’an compels Muslims to treat captives with dignity and compassion, “They fulfill their vow, and fear a day the evil of which is widespread. And they feed, for love of Him, the poor, the orphan, and the prisoner, Saying, ‘We feed you for Allah’s pleasure only. We desire no reward nor thanks from you.’” 
Islam abolished the pre-Islamic custom to continuously imprison POWs well after the war ended. Islam forbids holding captives outside wartime—such captives must be liberated immediately. Applying this teaching to contemporary times, any POW captured during any wars would categorically need to be released when the war is over. Judging by what is actually done by modern warring nations, far from an unjust practice, this teaching is in danger of being called too liberal and free.
 Sir William Muir, The Life of Mahomet Page 233-34 (1878).
 Qur’an 8:68.
 Qur’an 76:8-10.