Very few Civil War farmers went home to take care of the crops and then returned to fight. The American Civil War was far longer and more destructive than virtually anyone expected. At the outset of the war, many eager volunteers signed 90-day papers, evidence of the widespread belief that the war would be brief and nearly bloodless. Instead, the struggle stretched nearly four full years. Between 1861 and 1865, the Union and Confederacy mobilized more than three million men for the fighting and suffered some 600,000 deaths. The war remains the bloodiest conflict America has ever fought.

One of the reasons for the dramatic increase in the length of the war, the size of the armies, and the magnitude of the casualty rolls was the technological improvements in agricultural production that occurred in the decades leading up to the war. In the eighteenth century, the food demands of the population at large served as an important limit on the amount of manpower that could be mobilized into the army and on the length of time those armies could be maintained in the field. In those years, a nation that diverted a large proportion of its agricultural labor force to the military and kept it in the field for months at a time risked deprivation and starvation on the home front.

A bevy of technological improvements that appeared in the first half of the eighteenth century—iron and steel plows, seed drills, cultivators and, most importantly, mechanical reapers and threshers—made it possible to increase the amount of food that could be produced manyfold. By the mid-1800s, two men equipped with a horse and the new agricultural machinery could produce as much grain in a day as twenty men could harvest by hand using sickles in the late 1700s. Together, these changes dramatically altered the proportion of the population required for agricultural production. Three-quarters of American workers labored on farms in 1820; by 1860, fewer than three in five worked in agriculture.

The massive shift in the demographics of food production helps explain how the Civil War armies could place so many men under arms and keep them in the field for years on end. The massive armies that contested the huge battles between 1861 and 1865 could fight so long in part because their members were not needed at home to plant and harvest crops: the divisions could stay on campaign without threatening the larger society with starvation. And the substitution of mechanical advantage and animal effort for human muscle meant that farm labor no longer required adult men. Younger children and women could now perform many of the tasks that formerly demanded male workers. In the south, the labor of four million African-American slaves helped support the armies in the field and freed the white population to continue fighting. While neither side offered exemptions to farmers, the South did institute the Twenty-Negro Law, which released a plantation owner or overseer whom managed more than twenty slaves from military service—powerful evidence not just of slavery’s importance in maintaining the Southern economy and war effort but of the persistent fears of slave insurrection.

This is not to say that soldiers never returned to their homes and farms during the war. Furloughs for the troops were not uncommon, often doled out as a reward for service. (In the winter of 1863-1864, a Union Army desperate for reenlistments offered a 30-day furlough to any soldier willing to sign on for an additional three-year term.) But those furloughs rarely coincided with the agricultural cycle: campaigning season usually ran from the spring to late fall—precisely the months of planting and harvesting—and armies found it easiest to grant furloughs once the armies had gone into winter quarters. Soldiers generally viewed furloughs as a chance to visit loved ones and to escape the stifling discipline of army life for a brief moment.

In the South, the deprivations of war affected individual soldiers more acutely. Non-slaveholding white farmers—those who farmed small parcels of land for sustenance, as opposed to large planters growing cash crops—frequently joined the army in the belief that they were defending homes and families from Yankee invasion. As the war dragged on, and Federal troops pushed deeper into the Confederacy seizing crops and blocking transportation lines, many of those families suffered intensely from the scarcity of basic supplies. When letters arrived from home telling of wives, children, and siblings threatened with starvation, many of those rebel soldiers elected to leave the ranks and return home to provide for their families. Those desertions—officially a capital crime in the eyes of the military system—became more and more widespread in the last years of the war; historians estimate that as many as one in three Confederate soldiers had deserted by the final months of the war. Very few of those deserters returned voluntarily to continue the fight.

John Hanson, who held the office that was known officially as "President of the United States in Congress Assembled" from November 5, 1781 to November 4, 1782, died in November 1783 long before the invention of photography. The African-American man in the photograph that you saw on a website could not have been this John Hanson.

The possibility remains that the John Hanson in question had one or more African ancestors, either known or not known to his colleagues or even to himself. J. Bruce Kremer, one of Hanson's biographers, states that Hanson's grandfather and his three brothers emigrated in 1642 from Sweden to the recently formed New Sweden settlement on the Delaware River with newly appointed Governor Johan Printz. Kremer points out that one of the Hanson brothers, Andrew, had the same name as "Andrew Hanson, freeman, who once worked as a farmhand" for New Sweden landowner and military leader Lieutenant Måns Kling, the owner of a tobacco plantation on the Schuylkill.

Whether this Andrew was the same man as John Hanson's great-uncle, "must be a matter of conjecture," Kremer concludes.

One could conjecture, therefore, that John Hanson had an African ancestor as he may have been related to a man described as a freeman, that is, a freed black slave. Yet, the term freeman, in the context of the 17th-century New Sweden colony, did not indicate a freed black slave, as one might assume. According to Gregory B. Keen of the Historical Society of Pennsylvania, who has researched and written about the New Sweden colony, "The 'freemen' (frimännen)— so called because they had settled in the colony entirely of their own will, and might leave it at their option—held land granted them in fee, temporarily not taxed, which they cultivated for themselves, being aided also by the [Swedish West India] Company with occasional gifts of money, food, and raiment." Such "freemen" were distinguished from criminals forced to leave Sweden who had to work for a few years in New Sweden before they were classified as frimännen.

Those who believe that John Hanson was black might argue that his signing of the Proclamation of the Freemen of Maryland lends credence to the claim of African heritage. The Freemen of Maryland, however, was not an association of freed black slaves but of men advocating resistance to what they perceived as British tyranny in the period that led to the colonists' break with England. On July 26, 1775, the Freemen of Maryland resolved that the American colonies "be put into a state of defense" and approved armed resistance to British troops.

The Internet provides proponents of conspiracy theories with a way to reach a vast audience. Googling the phrase "John Hanson first black president" retrieves more than 350,000 hits. One website argues that because Hanson's signature is not to be found on the Declaration of Independence or the Constitution, and that a black man appears in the engraving on the back of the two-dollar bill of the signing of the Declaration of Independence, therefore a conspiracy to keep knowledge of Hanson's African-American identity from the public must have occurred. Yet Hanson was not a member of the Constitutional Convention in 1776, the year in which all but one of the signers signed the Declaration. Hanson died before the Constitution was created. Hanson, however, as a delegate to the Constitutional Convention beginning in June 1780 did sign and ratify the Articles of Confederation on March 1, 1781. In addition, while the skin color of one figure on the back of the two-dollar bill is ambiguous, the engraving was based on the painting in the U.S. Capitol by John Trumbull of the signing of the Declaration. In the painting, none of the figures have black or brown skin.

Historians cannot claim to prove "beyond doubt" that occurrences in the past did or did not happen. In a recent book on historical epistemology, Allan Megill acknowledges that historians cannot provide proofs of absolute certainty to support knowledge claims about the past. "Some persons of hypercritical bent demand that all knowledge be certain knowledge," he writes. "Following established philosophical tradition, they take all certain knowledge to fall into one of two categories. These are, on the one hand, the immediately certain knowledge of one's experience and, on the other, the logical certainty that is accorded to valid deductive reasoning. Neither of these forms of certainty is attainable to historical knowledge, however." Even a seemingly indisputable factual proposition such as "Napoleon Bonaparte existed," Megill argues, cannot be proven with absolute certainty since the past cannot be experienced in the present and Napoleon's past existence cannot be proven using logical deductive reasoning.

Rather than look for proof "beyond doubt" of beliefs about the past, historians instead should try to determine how well beliefs in question help, in Megill's words, "make sense of the totality of the historical record." In cases in which two or more accounts are credible, he advises that "the responsible historian will clearly indicate that the matter is not beyond dispute."

Historians then will examine evidence that supports rival claims and judge which is the best explanation on the basis of such evidence, an operation he terms "inference to the best explanation." In cases in which one account "is far better at accounting for the totality of the data than the alternatives," he insists that "the historian has every right to claim that such-and-such was the case."

With regard to John Hanson, historians thus have the right to claim that he was not black, with one caveat. As with all European Americans, Hanson may have had African ancestors in the far distant past if the arguments of scientists who claim that all humans have roots in African hominids are to be accepted, as opposed to the views of scientists who offer claims that humans developed independently in multiple regions.