Military architecture, the design of defense
Military architecture today is a highly specialized field. Can you imagine a painter with no military training just hopping on a flight to Fort Bliss and putting up towers? Leonardo faced no such restrictions. During his time with Francesco Sforza in Milan, he designed buildings with various military reinforcements. His ability to design for the military endeared him to his patron—never a bad thing for an artist! One such building was a castle with a triple defense system. Between about 1487 and 1490, Leonardo sketched both a plan and a perspective drawing for one corner of this building. He made a point of showing two different angular fortifications, one extending over the corner of the fort and the other (which included a formidable moat) extending over part of the external wall.
His design included a series of cannons located on the overhanging wall, which allowed the castle defenders to shoot directly at all attacking forces. Leonardo also designed a triangle-shaped bastion, a structure that allowed the soldiers inside the fortress to defend the entrance. Leonardo’s drawing for this type of structure was probably based on existing buildings, and it dates to his time in Romagna as Cesare Borgia’s military engineer (between about 1501 and 1504). The design included three small structures, probably service buildings, on top of the main edifice. There were also a series of embrasures (openings for cannons) along the top wall.
But there’s more. Leonardo also designed an innovative staircase for use in a fortified tower. His scheme included four different ramps. Each path was independent of the others, allowing soldiers to go up or down the four-story tower without running into groups going in the opposite direction. This technique could improve the soldiers’ response times, as they would be able to move both troops and weapons quickly during an attack. Leonardo’s design for this structure, probably also done between 1487 and 1490, included both a perspective view of the tower with the staircases exposed, and a top plan view.
In about 1502, Leonardo designed an addition to a moat. And no, his solution didn’t involve just filling it with alligators! He did something much more interesting. He hid a cylindrical tower under the water, giving it a gently sloping roof that stuck up slightly above the water’s surface. This system allowed defenders inside the moat tower to fire weapons right across the water’s surface. Wet hay would cover the roof of the tower to protect against damage from incoming gunshots.
Before planes, trains, and automobiles
Renaissance inventors were at a crossroads, whether they knew it or not. Europe was slowly emerging from the Dark Ages, and there had already been several significant inventions. At the same time, some of history’s greatest achievements were yet to come. Leonardo, living fairly early in the Renaissance period, was on the leading edge of the era’s innovation. Against what backdrop can we view his inventions?
One of the most significant inventions of the Renaissance was the mechanical timepiece. Though Casio calculator wristwatches wouldn’t come along for a while yet, society was beginning to place more importance on an easy way to tell the time. Clocks were first created in the 1300s, but it was not until the 1580s that Galileo (a scientist and researcher from Florence) developed the idea for a pendulum. It wasn’t until the 1600s, long after Leonardo’s death, that the concept of the clock was further mechanized with the introduction of gears and screws.
Certainly, Leonardo and his contemporaries didn’t have access to most of the modern conveniences we take for granted today. One of the things most noticeably lacking was electricity, which was not discovered until the seventeenth century and not widely used until the late 1800s. The first standardized fuel type was probably fish oil used by ancient Romans and those who came after them, so in the absence of electric lighting, fuel-driven lanterns would have been a possibility for Leonardo. Candles, torches, and lamps were other popular light sources during the Renaissance years.
In terms of weaponry, Leonardo had the advantage of not starting from scratch. Military technology, even in ancient Rome, was years ahead of the general technology available to the rest of the population. Hand-powered weapons such as spears and arrows had been around for generations, and gunpowder was in use by the middle of the eleventh century, though it probably wasn’t used in Europe until the 1350s. This invention changed the course of warfare because it became nearly impossible to defend against guns with only hand-powered weapons. Leonardo’s designs for cannons, for example, were a response to the new way of waging war.
Eyeglasses were another significant Medieval and Renaissance invention. By the 1300s, guilds in Venice were regulating eyeglass production, which, at the time, were probably considered a luxury item. When Johannes Gutenberg’s invention of the printing press made reading into more of a hobby than a luxury, though, eyeglasses came into much higher demand. Everyone wanted to read, and their eyes needed to keep up with them! Readily available books were a major factor for Leonardo because he was able to read the writings of ancient masters and, in the process, create his own interpretations and additions. Plus, if books could be published easily, he could also publish his own writings. In addition to all of these other inventions, Leonardo used the growing worldwide interest in mechanics to utilize and explore water. Naturally, his concepts relied on existing research with water pumps, which were developed in the Middle Ages.
War games
When several Florentine forts were attacked in 1479, Leonardo became interested in ladders for scaling walls during an attack as well as methods for defending against those same efforts. Military engineering was just one of Leonardo’s many interests, but as with everything else, he dove into it wholeheartedly and came up with several important designs.
Leonardo designed a number of different ladders for wall climbing. Some were stiff, solid ladders, while others were flexible and made from rope. To attach securely to the top of the wall, some of Leonardo’s ladders had hooks; others had spikes on the base to keep them immobile on the ground. He also thought about flexible ladders that could hang from a wall as well as the type of chain ladder that’s often used for fire escapes today. Ladders were, in a way, a symptom of the problem: war. Leonardo got to the root of the issue and also designed entire defense systems. One of his most clever ideas involved ladders lining a wall, where the tops of the ladders were all attached to a bar. Leonardo’s assumption was that attackers would rush to climb the ladders in a sneak attempt to overtake the castle inside. Not so fast! Leonardo’s defensive soldiers would push the bar out, and any poor, unsuspecting attackers would fall to the ground along with the row of ladders. It sounds complicated, and it was; perhaps this overdesign was one of the reasons it was never tested.
During his time with Duke Sforza, Leonardo also designed bridges for military applications. Some of these were portable; troops could carry the bridges with them and set them up quickly when needed. Others were designed to be particularly strong and resistant to fire or other means of destruction. Leonardo also considered methods to burn and destroy enemy bridges.
Leonardo’s military bridges had a number of different designs. One was arched in such a way as to be particularly strong when assembled. Others used traditional pilings, or were flexible so they could swing without breaking. Leonardo also designed adjustable jacks for opposite sides of a river, to be used if the banks were different heights on each side.
Leonardo designed one particularly massive bridge during his time with Cesare Borgia. In order to connect the Golden Horn and the Bosporus, Leonardo suggested building a huge bridge across the Gulf of Istanbul. This route would have had immense strategic importance, but other engineers vetoed the plan when they saw how large the bridge would have to be. Nevertheless, modern studies show that the structure would have been possible to build with the resources of that era, and the bridge itself would have been solid and well designed.
Vehicles that could serve offensive or defensive purposes also piqued Leonardo’s design curiosity. Take, for instance, his design for a horse-drawn chariot, which had four large scythe-like blades mounted to the axles. As the horse pulled the chariot, the blades would rotate, slicing off the limbs of enemy soldiers. A similar design placed the four large blades at the front of the machine, in front of the horses even, where a screw-type device turned them, and included a series of smaller scythe blades placed at the back of the chariot. This chariot was designed as a brutal weapon, indeed. Even the initial sketches included images of dead and dying soldiers left in its wake. For the peace-loving Leonardo, this was an incredibly gruesome design!
Building a better …cannon?
Leonardo’s peaceful, harmonious landscape paintings do not tell the entire story of his career. In addition to his work to support troops with better ladders and bridges, Leonardo also designed or improved weapons. Guns, cannons, and other artillery weapons were on the rise during the Renaissance. Newer was better, especially when it came to national defense. Leonardo appeared to have had a nostalgic side, though, because he still spent time working to perfect or improve older weapons such as catapults, slingshots, and crossbows.
One of his innovations was the rapid-firing crossbow. This was no ordinary crossbow—it actually included four crossbows and got its power from a large treadmill. A number of men walked on steps that were located around the outside of a large wheel, and as they made the machine rotate, an archer would fire each crossbow, reloading them in sequence.
Leonardo also designed a mammoth seventy-six-foot crossbow, which required six wheels to maneuver it. This device, also called a ballista, used a series of gears to draw back the bow; a simple strike of a pin would release the shaft. Leonardo believed that this giant weapon would operate in almost complete silence, but his claim was never tested because the device was too difficult to build given the abilities of the day.
In the interest of defeating more enemies faster, Leonardo designed a rapid-loading catapult system. This machine, which could be mounted on top of a wall, consisted of a rope and winding mechanism used to bend back the arm and, in effect, ease the firing process. Leonardo also designed a row of catapults that could be launched at the same time when hit with hammers. Specially designed missiles, with gunpowder inside, had fins on the tail for extra stability, and when they hit their target, strikers inside ignited the gunpowder and caused an explosion. These sound remarkably similar to modern artillery shells.
While cannons were used as early as 1346, they weren’t very advanced by Leonardo’s time. They were still simple cylinders that used an explosion of gunpowder at one end to propel a stone ball out the other. One of Leonardo’s first improvements to cannon design was to create a model that could be loaded from the back, rather than down the front of the barrel. Since the cannons had to be cooled before they could be reloaded, Leonardo suggested putting them in a vat of water to cool them off quickly. Not a bad idea, but would you want to be the one to lift a hot cannon into a tub?
In his studies of cannon balls, Leonardo was one of the first to explore ballistic trajectories. He studied how changing the angle of the cannon’s muzzle could affect the distance the cannonball traveled, and in testing his designs, he supposedly launched a test cannonball 10,000 feet high!
Another invention of Leonardo’s was a steam-powered cannon. The end of the cannon was heated to a very high temperature, and then a small amount of water was placed inside. As the water turned to steam, the increased pressure shot out the speeding cannonball. Leonardo’s notebooks include information on the size of cannonballs that the device could use, and the distance they could travel. These details suggest that, unlike most of his inventions, this one was actually built and tested.
One problem that plagued Leonardo was that cannons had a large delay between repeated firings. Leonardo’s answer was, in retrospect, pretty obvious: He proposed a system with multiple cannons that could either be fired all at once, or one after another. His designs included eleven or fourteen guns in three rows: While the top row was being fired, the middle row could be reloaded, and the bottom row cooled off. These systems are considered to be the predecessors of today’s machine guns. Just think about how dangerous Leonardo would be today if he were making improvements to modern military technology!
A coach fit for a king
Besides his designs for the bicycle and automobile, Leonardo created drawings of other vehicles. As engineers rose to the challenge of making more advanced war machines, Leonardo also contributed significantly to this effort. Leonardo designed new weapons and entirely new weapons systems and also came up with ideas for many different land vehicles. Some of his ideas were quite practical, while others appear more inventive, like modern automotive “concept cars” that are cool to look at, but would never be practical on the highway.
One of his largest vehicular designs was for an armored tank. The idea behind the armored car was simple: Protect passengers while causing as much damage as possible. Leonardo didn’t specify the powering mechanism, and his notes indicate that his tank could have been either hand-cranked (as with his automobile design) or drawn by horses. If hand powered, the cranks would have been connected to gears, which, in turn, connected to the main driving wheels. Clad in metal panels, like today’s tanks, it would have had holes for guns to poke through. In the drawing, it looks like a combination of a turtle and an alien spaceship. Do you think this vehicle would have struck awe, or just confusion, in the enemy?
Leonardo also designed vehicles for civilian usage. As architectural technology developed, the construction trade had to keep up. Lifting heavy materials to increasing heights was a well-documented problem throughout the Medieval period (just think about all those cathedrals!), and Leonardo came up with several ideas to remedy the situation. He sketched a number of designs for cranes that could be used for quarrying. The crane would lift a stone block out of the ground, and then a mechanism would automatically release once the load was removed from the quarry pit. Leonardo also drew three-dimensional designs for cranes that pivoted on a platform, which would have been useful for constructing tall buildings. While there don’t appear to have been any crane models built during Leonardo’s lifetime, later engineers have built them from his specifications and found them to be nearly flawless.
