Giant crossbow
A letter from the west coast of India addressed to the
Florentine regent Giuliano de’ Medici in 1515 is revealing. A seafarer named
Andrea Corsali reported that he had discovered gentle people clad in long robes
who lived on milk and rice, refused any food that contained blood, and would
not harm any living creature—“just like our Leonardo da Vinci.” Corsali was
describing the Jains, known for their extreme nonviolence; in the twentieth
century they would have a profound influence on Mahatma Gandhi.
One of Vasari’s loveliest anecdotes about Leonardo concerns
the artist’s love of animals: “Often when he was walking past the places where
birds were sold, he would pay the price asked, take them from their cages, and
let them fly off into the air, giving them back their lost freedom.” Did
Leonardo, who had an exceptional desire for freedom and himself tried to fly,
feel a special rapport with birds?
Of course Corsali would not have been reminded of the artist
far away if Leonardo’s attitude had not seemed so remarkable. That a person
would display empathy at all was quite unusual in this era, which had been
devastated by violence. But the idea of actually forswearing the consumption of
meat out of simple consideration for other creatures was unheard of in the
West.
Vasari, who later wrote a biography of Leonardo, may have
known these and other reports about customs in the Orient. In the Buddhist
countries of Southeast Asia birds are offered for sale in front of some temples
even today so that people who want to ensure good karma can buy their freedom
and send them soaring into the air. Vasari’s account of Leonardo’s bird
liberation may have been no more than an appealing embellishment to his text.
Still, there is no doubt that Leonardo had a deep-seated
aversion to all violence, as several passages in his notebooks confirm. His
attitude certainly had more in common with the ethos of Eastern nonviolence
than with the harsh customs then prevalent in the Christian West. Precisely
because he respected the value of every creature, he was firmly convinced of
the sanctity of human life. In reference to his anatomical studies, he wrote:
“And thou, man, who by these my labours dost look upon the marvelous works of
nature, if thou judgest it to be an atrocious act to destroy the same, reflect
that it is an infinitely atrocious act to take away the life of man.”
Scythed chariot
Leonardo’s words make it difficult to grasp the gruesome
fantasies his mind was capable of in designing his engines of war. On hundreds
of pages, Leonardo sketched giant crossbows, automatic rifles, and equipment to
bombard strongholds with maximal destructiveness. The sole function of these
devices was to kill and destroy. He did not just record the technology, but
provided graphic descriptions of the devastating impact of his inventions. In
one sketch, archers are running away from an exploding grenade, which Leonardo
referred to as “the deadliest of all machines.”4 In another, a war chariot with
rotating scythes as large as men is mowing down soldiers and leaving behind a
trail of severed legs and dismembered bodies.5 The battle plans Leonardo drew
up are equally chilling. On Sheet 69 of Manuscript B, housed in Paris, we read
about his preparations for chemical warfare:
Chalk, fine sulphide of arsenic, and powdered verdigris may
be thrown among the enemy ships by means of small mangonels. And all those who,
as they breathe, inhale the said powder with their breath will become
asphyxiated. But take care to have the wind so that it does not blow the powder
back upon you, or to have your nose and mouth covered over with a fine cloth
dipped in water so that the powder may not enter.6
His involvement in the wars of his era extended well beyond
the design of weapons and began even before he signed on with the in – famous,
bloodthirsty Cesare Borgia in 1502. How could a man whose sense of empathy is
said to have inspired him to free birds from their cages come up with ideas of
this sort?
On one occasion, Leonardo justified his military activities
with a statement that a modern-day reader could easily picture coming straight
from the Pentagon: “When besieged by ambitious tyrants, I find a means of
offense and defense in order to preserve the chief gift of nature, which is
liberty.”
Doubts are certainly warranted here; after all, his first
employer, Ludovico Sforza, was not exactly a champion of freedom. The historian
Paolo Giovio, a contemporary of il Moro, called him “a man born for the ruin of
Italy.” That might sound harsh, but without a doubt, “the Moor” was a major reason
that Italy lost its freedom for centuries and became a battlefield for foreign
powers.
Ludovico, an inveterate risk-taker, sized up his position on
his very first day in power and realized that he was surrounded by enemies. In
his own empire his right to rule was in dispute, since he owed his power to the
violent murder of his brother, for which no one had been charged, and the
arrest of the sister-in-law. Moreover, Venice and the Vatican tried to exploit
Ludovico’s insecure position, and they armed for war. In March 1482, the
Venetians attacked Ferrara, which was an ally of il Moro. At this time,
Leonardo arrived in Milan and in his famous ten-point letter of application
promised il Moro a whole new arsenal of weapons. Two years later, Ludovico was
able to defeat the Venetians.
But il Moro, who was focusing all his efforts on
legitimating his rule once and for all, needed a seemingly endless supply of
weapons. Over the next few years, his dodges would determine not only the
further course of Leonardo’s unsettled life but also result in the so-called
Italian Wars, which lasted sixty-five years and brought about the political
collapse of the country.
The disaster ran its course when Ludovico sought a strong
ally against Naples. The king of Naples, Ferdinand I, had meanwhile given his
daughter’s hand in marriage to the legitimate heir to the throne in Milan, Gian
Galeazzo, and was quite indignant when he realized that Ludovico had no
intention of ceding power to his son-in-law. Ludovico encouraged Charles VIII of
France to invade Italy to overthrow Ferdinand. What followed was a bloody
farce: Charles was asked to invade Lombardy with forty thousand soldiers,
whereupon Gian Galeazzo was murdered. Two days later, Charles declared il Moro
the legitimate duke of Milan. But the latter showed no gratitude. When the
Neapolitans rebelled against the French occupation in the following year, the
opportunist switched sides and entered into an alliance with Venice and the
pope. The French were expelled and suffered great losses.
Just a few decades earlier, wars had been highly ritualized
battles with relatively few casualties, but now they were developing into
horrific bloodbaths. The handgun had been widely adopted; a few years later,
Leonardo would contribute a wheel lock, which was one of the handgun’s first
effective firing mechanisms. And there were growing numbers of portable cannons
on battlefields. Since the earlier stone balls had been replaced by metal
projectiles, the firearms shot more effectively than ever before, as Charles
VIII’s soldiers proved when they demolished the ramparts of the mighty castle
of Monte San Giovanni Campano with small cannons within hours, before attacking
Naples. Until then the battle was won by the side that had more and better
soldiers. From this point on, technology was key.
Leonardo had promised marvelous weapons to il Moro and was
granted a tremendous degree of freedom in return. As the engineer of the duke,
he received a fixed salary and no longer had to rely on selling his art on the
market. This was the only way he could pursue his research interests and
continue to perfect his paintings without any pressure to meet deadlines. We
owe the magnificence of the Milan Last Supper, the studies of water, and his
explorations of the human body to Leonardo’s clever move of offering himself up
to one of the most unscrupulous warlords of his era. During his first seventeen
years in Milan, serving Ludovico, he sketched the great majority of his
weapons, among them his most dreadful ones.
All the same, Leonardo’s interest in weapons went far beyond
the steady job they brought him. His drawings reveal an unmistakable
fascination with technology. In the end, his inventions were the product of his
inexhaustible fantasy, which gave rise to paintings, stories, projects to
transform entire regions, tools—and weapons. One of these weapons, which he
designed in Milan, looks like a water mill, but is actually a gigantic
automatic revolver. Leonardo arranged four crossbows in a compass formation,
with one pointing upward, one downward, one to the left, and one to the right.
The wheel was powered by four men running along its exterior to turn it at
breakneck speed. An ingenious mechanism with winches and ropes caused the bows
to tighten automatically with each turn. The marksman crouched in the middle of
the mechanism and activated the release. In one version, the wheel was equipped
with sixteen rather than four crossbows. Leonardo devoted himself to refining
the driving mechanism as well.
Even so, in comparison with the truly revolutionary firearms
of the era, this contraption looks charmingly old-fashioned. At least for the
years until 1500, Kenneth Clark was probably right in claiming that Leonardo’s
knowledge of military matters was not ahead of his time. Even Leonardo’s most
spectacular weapon, the giant crossbow he invented in 1485, was not really
pioneering. With a 98-foot bow span, this monster was intended to stand up to
cannons, to fire more accurately, and to save the soldiers from often fatal
accidents with exploding gunpowder. There is no evidence, however, that anyone
attempted to construct this giant crossbow during Leonardo’s lifetime. More
than five hundred years later, when a British television production undertook
this project, the results were pitiful. Specialized technicians were brought in
to build a functionally efficient weapon using twentieth-century tools, guided
by Paolo Galluzzi, one of the leading experts on Renaissance engineering. Since
they were required to restrict their materials to those that were available in
the Renaissance, they opted to build a bow with blades made of walnut and ash
that would be five times larger than any before. A worm drive designed by
Leonardo himself had to muster a force equivalent to the weight of ten tons to
tighten this enormous spring, thus making it possible to catapult a stone ball
over 650 feet. But when British artillerymen tried out the construction on one
of their military training areas, the balls barely left the weapon. After a
mere 16 feet in the air, they plopped to the ground. Video recordings showed
that they could not detach properly from the bowstring. When the technicians
added a stopping device to the string (not drawn by Leonardo), the range
increased to 65 feet— still hardly sufficient to produce anything but guffaws
on a Renaissance battlefield. And the fact that the replicators had made the
bow thinner than in Leonardo’s design came back to haunt them—the wood broke.
When you look at many of Leonardo’s drawings from his years
in Milan, it is hard to shake the feeling that Leonardo had no intention of
supplying serviceable weapons. It seems to have been far more important to him
to impress his patron—especially when he emphasized the enormous dimensions and
the impact of his weapons. As the most talented draftsman of his generation, he
knew how to create a dazzling effect. Leonardo enjoyed an outstanding
reputation as a technician of war because he was a great artist. He portrayed
the details of his designs so meticulously, using the effects of perspective,
light, and shadow so skillfully, that it was easy to mistake reality for wish.
The drawing of the giant crossbow features not only the knot of the string and
the details of the trigger mechanism, but also the soldier handling the weapon.
Like the face on the Mona Lisa, Leonardo’s war machines seem alive.
THE PHYSICS OF DESTRUCTION
While Leonardo proved a master of illusion in designing
weapons, he also made concrete contributions to military development. Military
commanders needed to figure out how to put the latest firearms—mobile
cannons—into action. How should they shoot? With bows and crossbows, the
shooter simply aimed straight ahead; the range of the new firearms, by
contrast, meant that the trajectory curve had to be determined to make the
cannonball hit its target. But no one had a clear idea about the laws governing
the paths of cannonballs. Progress on this matter could determine the outcomes
of wars.
Traditional physics offered little help, because this
discipline still adhered to the ancient view that a body moves only while a
force acts on it. But if that were so, a cannonball would come to a standstill
just after leaving the barrel of the cannon. The seemingly plausible concept of
“impetus” was introduced: The cannon gives the ball its impetus, and only when
the impetus is completely used up as it flies through the air does it fall to
the ground. The cannoneers of the time were well aware that the impetus theory
could not be correct; anyone who relied on it was off the mark. The error is
that gravity sets in immediately to begin pulling down on the cannonball.
Leonardo’s interest in this question went far beyond its
military implications. He was determined to figure out the laws of motion. He
kept going around in circles because he could not relinquish the idea of
impetus and because the crucial concept of the earth’s gravity was still
unknown at the time. His notebooks document how bedeviled he was by the laws of
motion. His explanations of mechanics were riddled with inconsistencies; at
times he argued both for and against impetus within the space of a single
paragraph.
But then he had a brilliant idea of how to determine the
trajectory of projectiles not by conceptualizing, but by observing: “Test in
order to make a rule of these motions. You must make it with a leather bag full
of water with many small pipes of the same inside diameter, disposed on one
line.” One sketch shows the small pipes in the bag pointing upward at various
angles, like cannons that aim higher at some points and more level at others.
The arcs formed by the spurting water correspond to the trajectories of the
cannonballs. Leonardo’s trajectories were accurate in both this sketch and
others. By means of a clever experiment—not involving mathematics—he had
discovered the ballistic trajectory that Isaac Newton finally worked out
mathematically some two hundred years later.
This little sketch offers a glimpse inside Leonardo’s mind.
He was able to link together fields of knowledge that appeared utterly unrelated.
From the laws of hydraulics, which he had investigated so exhaustively, he
gained insights into ballistics. His thoughts ran counter to the conventional
means of solving problems. Instead of attacking the matter head on, formulating
the question neatly, and penetrating more and more deeply below the surface,
Leonardo approached the problem obliquely—like a cat burglar who has climbed up
one building and from there breaks into another across the balconies. Leonardo
was unsurpassed in what is sometimes called “lateral thinking,” which enabled
him to explain the sound waves in the air by way of waves in the water, the
statics of a skeleton by those of a construction crane, and the lens of the eye
by means of a submerged glass ball.
Leonardo’s experiments with models also represented a new
approach. Since he neither understood how to use a cannon nor was able to
observe the trajectory of an actual cannonball up close, he used a bag filled
with water as a substitute. Of course an approach of that sort is unlikely to
yield a coherent theoretical construct, because similarities between different
problems are always limited to individual points, and Leonardo was far too
restless to pursue every last detail of a question. Still, his models yielded
astonishing insights. The French art historian Daniel Arasse has aptly called
him a “thinker without a system of thought.”
In an impressive ink drawing, Leonardo illustrated the
damage that could be inflicted by applying his insights into ballistics. A
large sheet in the possession of the Queen of England shows four mortars in
front of a fortification wall firing off a virtual storm of projectiles. Not a
single square foot of the besieged position is spared from the hundreds of
projectiles whizzing through the air. For each individual one, Leonardo marked
the precise parabolic trajectory, and the lines of fire fan out into curves
like fountains. Ever the aesthete, Leonardo found elegance even in total
destruction.
Saturation bombing of
a castle
It is difficult to establish to what extent Leonardo’s
knowledge of artillery was implemented on an actual battlefield. When Ludovico
had Novara bombarded in February 1500, the mortars were so cleverly positioned
that the northern Italian city quickly fell. In the opinion of the British
expert Kenneth Keele, il Moro was using Leonardo’s plans for a systematic
saturation bombing.
Leonardo’s close ties to the tyrants of his day offer a case
study of the early symbiosis of science and the military. Now as then, war not
only provides steady jobs and money to pursue scholarly interests, but also
prompts interesting theoretical questions. Even a man as principled as Leonardo
was unable to resist temptations of this sort. He was not the first pioneer of
modern science and technology to employ his knowledge for destructive aims.
Half a century earlier, Filippo Brunelleschi, the inspired builder of the dome
of the Florence Cathedral, had diverted the Serchio River with dams to inundate
the enemy city of Lucca. (This operation came to a disastrous end; instead of
putting Lucca under water, the Serchio River flooded the Florentine camp.)
Leonardo’s struggle to strike a balance between conscience, personal gain, and
intellectual fascination seems remarkably modern, and brings to mind the physicists
in Los Alamos who devoted themselves heart and soul to nuclear research until
the atomic bomb was dropped on Hiroshima.
Of course we cannot measure Leonardo’s values by today’s
standards. We have come to consider peace among the world’s major powers a normal
state of affairs now that more than six decades have passed since the end of
World War II, but we need to bear in mind that there has never been such a
sustained phase of freedom from strife since the fall of the Roman Empire. In
Italy, the Renaissance was one of the bloodiest epochs. The influence of the
Holy Roman Empire had broken down, mercenary leaders had wrested power from
royal dynasties, and a desire for conquest seemed natural. War was the norm,
and a prolonged period of peace inconceivable.
Leonardo’s refusal to regard death and destruction as
inescapable realities is a testament to his intellectual independence from his
era. As far back as 1490 he was calling war a “most bestial madness.” And one
of his last notebooks even contains a statement about research ethics. While
describing a “method of remaining under water for as long a time as I can
remain without food,” he chose to withhold the details of his invention (a
submarine?), fearing “the evil nature of men who would practice assassinations
at the bottom of the seas by breaking the ships in their lowest parts and
sinking them together with the crew who are in them.” The only specifics he
revealed involved a harmless diver’s suit in which the mouth of a tube above
the surface of the water, buoyed by wineskins or pieces of cork, allows the
diver to breathe while remaining out of sight.
Leonardo must have had his reasons for withholding
particulars about the dangerous underwater vehicle. Perhaps his ideas were
still quite vague, or he was afraid that imitators might thwart his chances for
a promising business. But the key passage here is Leonardo’s statement about
the responsibility of a scientist. He was the first to assert that researchers
have to assume responsibility for the harm others cause in using their
discoveries. Insights like these, and his high regard for each and every life,
were quite extraordinary at the time. It is amazing that he embraced these
ethical principles—but not surprising that he repeatedly failed to live up to them,
at least by today’s standards.
