Lights, Signs and Slaughter

This is the first of what is aiming to be an occasional series of shortish posts appearing on both the author's blog and on this site, and which will be of a historical and cultural, rather than a scientific nature. It's astronomical relevance will only gradually reveal itself...

Fredericksburg, Virginia, is a small American city on a southern bend of the Rappahannock river, with a modern population roughly that of modern day Ely. It is apparently a pleasant place to visit, with fine historic houses, small museums and a thriving local art scene. In December 1862, however, its situation - almost exactly half way between Washington and the Confederate capitol at Richmond - led to its becoming the site of a particularly horrifying battle.

The American Civil War has long interested me, not so much for its specifically military aspects (though these are certainly fascinating) as for its social and political background. On April 12th of 2020, it occurred to me that I could fill a good part of my unexpected lockdown leisure by following it's course on an almost day by day basis, with the help of the extremely detailed battle accounts to be found on Wickipedia, the video reconstruction site Warhawk and, for the larger context, James McPherson's authoritative history, Battle Cry of Freedom. I must say, I found the four year exercise compelling.

Fredericksburg (or, as it is sometimes know, the First Battle of Fredericksburg, since there was to be a subsequent clash in the vicinity a few months later) was the last major engagement of 1862, a year that had started out with great promise for the Union, but had gradually bogged down in frustrating siege action. From March through to July, the Union Army of the Potomac had made extraordinarily heavy weather of a direct assault upon Richmond, most Northerners attributing the campaign's eventual collapse to the reluctance of General George B. McLellan to commit his forces to the field. Dismayed and exasperated at his Chief of Staff's lack of decisiveness, and desperately in need of a victory, President Lincoln replaced him with someone of altogether less cautious character - Ambrose E. Burnside.

Burnside was a "political" general, owing his rapid promotion to his standing as a local dignitary, rather than any military experience. Still, he had achieved an impressive feat in his seizure of strategically important islands off the Carolina coast and enjoyed a considerable popular following. Despite his outward flamboyance - he gave his inverted name to the distinctive style of facial hair he himself magnificently sported - he was by no means confident that he was the right man to assume overall strategic command. Tragically, this lack of self-belief was to prove amply justified.

McLellan having failed to to take Richmond by advancing from the coast, Burnside planned an audacious Winter assault from the opposite direction, via Fredericksburg. This, however, would involve a mass fording of the unpredictable Rappahannock, and Union engineers were slow in meeting the sudden demand for pontoons and portable bridge sections with which to effect it. The delay pushed back the crossing to the bitter middle of December, whilst giving Confederate forces, under their two most resourceful commanders - Robert E. Lee and Thomas "Stonewall" Jackson - time to spring a trap.

When blue uniformed troops finally made their way across the river on December 11th they found Fredericksburg held by just a small and easily dispatched enemy garrison. Lee had massed the bulk of his forces in near-impregnable positions on Marye's Heights, overlooking the town, with Jackson holding lower ground to his South. December 13th saw the Union's best efforts to overwhelm Jackson undone by poor communications along the chain of command. Casualties were shocking and, as evening fell, the sage grass, despite the cold, proved dry enough to catch fire, burning many wounded men alive. Meanwhile, on the Heights themselves things were going no better, with Burnside's obdurate refusal to abandon his assault upon a massively defended stone wall resulting in a quite horrific slaughter. The dead were piled up on the lower slopes; concentrated Confederate fire prevented the living from making a safe retreat.

"It is well that war is so terrible", remarked Lee as he surveyed the carnage, "or we should grow too fond of it", an indication that - even by the standards of a conflict that had already witnessed the bloody devastation of Shiloh and Antietam - this had been an appalling battle. Burnside, having presided over the loss of over 12,000 men, spent the next day contemplating a final desperate charge to be personally led by himself, but was talked out of it. (A month later he would be relieved of command, his reputation in tatters and having acquired the unenviable nickname "Butcher of Fredericksburg".) Instead, that evening he successfully petitioned Lee for permission to gather up his wounded in preparation for withdrawal.

On the night of December 14th the freezing air was filled with the cries and howls of grotesquely injured men, as they lay out, piled up in the fields, surrounded by the corpses of those already dead. Many more would die on the ignominious retreat ahead. And then, as their colleagues and hospital staff did their best to attend them, something strange and spectacular illumined the nightmarish scene - what appears to have been a particularly vivid display of the Northern Lights.

At 38 degrees of latitude, Fredericksburg lies unusually far south for a visitation by the Aurora Borealis, but not impossibly so. There had been at least two reports of the lights' appearance in Virginia during the 18th Century, and the 1850s and 60s seem to have coincided with unusually turbulent geomagnetic activity. In September 1859 - less than two years before the outbreak of the Civil War - the most powerful magnetic storm ever recorded saw the appearance of fantastically bright auroras all across the North American landmass and as close to the equator as Colombia. Perhaps it is not surprising at a time of mounting political tension that many took these lights in the sky to be omens of impending doom. On that freezing December night at Fredericksberg, witnesses on both sides of the field reported the phenomenon to be of quite outstanding beauty and majesty, but tended to attach differing symbolic interpretations to it. For most Unionists, it represented a solemn heavenly tribute to the courage of their slain comrades, whilst for Confederates it was more like a celebratory firework display in honour of their victory. How many of either army literally thought these celestial illuminations were a supernatural reflection of affairs on Earth we cannot know, though most of them probably subscribed to an anthropocentric view of Nature in which God could - should he so choose - intervene directly in the workings of his creation. Our own view of such cosmic manifestations may be altogether more scientifically informed and secular, but surely they were right to feel that the great polar auroras have something important to tell humanity about its privileged tenure on the planet it inhabits.

Although images in prehistoric cave painting suggest that celestial auroras had been observed with the naked eye at least 30,000 years ago, it was not until surprisingly recently that their cause was fully understood. It was Kristian Birkeland - a talented, if eccentric Norwegian physicist who also conducted open-minded research into paranormal phenomena - who first suggested that energised solar particles travelling at unimaginably fast speeds regularly came into violent contact with the Earth's ionosphere, producing auroral electrojets that are then conducted along geomagnetic field lines into and away from the polar regions. The ridicule directed at this theory by much of the international scientific community upon its publication in 1908 appears to have intensified the paranoid depression Birkeland was already prone to. His mysterious death in 1917 at the age of 49 was almost certainly suicide. It was not until experiments carried out by the US navy in the 1960s that he was fully vindicated. The field aligned currents he postulated do indeed exist and are now named after him. The concentration of solar energy they direct towards the poles causes the atoms and molecules of the Earth's atmosphere to fluoresce in colours determined by chemical composition.

A further suggestion of Birkeland's, that supposedly "empty" space was not - as previously assumed - an attenuated near-vacuum, but filled with volatile plasma, has opened up vast areas of cosmic investigation that are still being energetically pursued. What we see in the Polar Auroras are vast accumulations of such radioactive matter being deflected by the Earth's complex - and still little understood - magnetosphere. Perhaps the scientist's Norse ancestors who had imagined the lights to be reflections off the shields of the Valkyrie were not so wide of the mark. Nature's greatest terrestrial light show is a sign of our protection from forces utterly inimical to human continuance. Every sighting of them should - like the luminous images of a pale blue Earth recorded by astronauts - make us aware of how fragile and singular our densely inhabited world is.