We presume that many of our readers have noticed the recent debate in the Congress of the United States on the subject of retaliation upon rebel prisoners of war in our hands for the treatment ours have received from the rebel authorities; and we think not a few must have been surprised at the course of that discussion. That opinions on this subject should differ is very natural; but so very wide a difference, or rather a direct conflict of opinion, on fundamental principles, would suggest that either the law itself was unsettled, or that the speakers did not well understand it. Indeed, on these questions of the laws and usages of war there is great want of information, not only among our people generally, but among our legislators, courts, lawyers, military officers and other public men. Nor is this to be wondered at. Prior to the present war, the people of the United States made no claim to be a military people; on the contrary they prided themselves as being civil in the strict sense of that word, and disclaimed and discountenanced all knowledge of the military art, or acquaintance with the science of war. Indeed, a profound peace of more than three-quarters of a century could scarcely be said to be interrupted by the insignificant contest of 1812, or the short war with the weak and demoralized Eepublic of Mexico. During this long period our pursuits as a nation have been, not of arms, but of agriculture, manufactures and commerce. Moreover, our very astute politicians and legislators have assured us, time and again, that there was no necessity for any military organization or military knowledge in the United States, for our untrained militia were more than sufficient for any contingency that could possibly arise. It is true that Washington and his contemporaries who achieved our independence and founded the Eepublic took a different view of this question; but who would presume to compare their opinions with those of the sages who lead our modern Congressional debates!