The Man Who Broke Napoleon's Codes (25 page)

The use of a 1,400 number cipher by the French marked an enormous advance. While Napoleon's army was the best organized and the most scientifically perfected the world had ever known, it had never before used ciphers of more than 200 characters for military operations
(imperial diplomacy was another matter). The new cipher would make life much harder for someone who had cracked the Army of Portugal's 150-figure code, especially since the Great Cipher allowed so many permutations in the writing of any simple phrase or even of any single word. Taking the example of
Seville,
it could be encoded as:

The different approaches could be combined, and within one and the same dispatch the astute user could encode a recurring word differently each time. In addition, the cipher retained a few vacant numbers that could be put randomly into the middle of a word to make code-breaking guesswork even harder.

In short, the design made it extremely hard to deduce anything from the length of a coded passage or the numbers used to encipher it.
Seville,
as we have seen, could be turned into anything from the single number 1359 to any number of variations up to seven or eight figures. Even if the person using it made a mistake as crass as the one in General Montbrun's letter of August 1811 to the governor of Ciudad Rodrigo (mixing code and
en clair
in an obvious reference to “H.E. Marshal the Due of Ragusa”), it would be far less damaging in this new cipher than before. For whereas that mistake had revealed 21 code numbers in a 150-figure cipher, the same phrase in Joseph's
Grand Chiffre
would only compromise one or two out of 1,400 numbers. It was a code of such strength that Napoleon considered it safe to send letters about matters of the utmost importance in the hands of some local peasant. Such a messenger would rarely arouse suspicion, and if he proved to be a traitor and delivered his precious missive to the enemy, nothing would be lost.

In sending out the tables, Marshal Berthier urged the recipients to keep the secret tables in their private papers and only allow a trusted individual of their retinue to learn their workings. He also sent instructions together with the ciphering tables adding one or two tricks of the trade to help an inexperienced cipher secretary. The most cunning read, “When finishing the ciphering by the code that marks the end, add a certain number of vacant codes of your choice after it.” This anticipated that a decipherer might well attack the end of a letter first, since there were standard forms of signing off, such as “be assured, sir, of my highest esteem and consideration.” Clearly, anyone trying to crack the code this way would be wasting their time on meaningless code numbers.

Once put into action, King Joseph's new code marked a great step forward in the security of communications. It applied to the military sphere those lessons that had been learned during the evolution of diplomatic ciphers during the previous two centuries.

Napoleon's orders to Marmont to march his men to the southeast in support of the Valencian operation arrived in several installments in early and mid-December 1811. They were not protected by the Great Cipher, but this did not matter since it seems that none of these critical dispatches were intercepted. One by one, French battalions began breaking camp and forming into their constituent regiments. Then they began tramping down to La Mancha, where a force of two infantry divisions and one of cavalry (nine thousand troops or thereabouts) was being formed.

The French movements were detected by spies. Guides carrying scribbled notes came clattering into Frenada's little square, tethered their exhausted mounts and delivered each morsel of information to the door of Wellington's headquarters. The first really reliable report arrived on 24 December: one of the southernmost divisions of the Army of Portugal had moved out of its usual cantonments and away from the Portuguese frontier.

In Frenada and the other villages of the border country, British troops sat down to their Christmas dinners. For many, the preferred bill of fare was lean roast beef followed by plum pudding. Others opted for a roast goose or game birds. Good claret flowed freely, and the low-ceilinged Portuguese farmhouses were crowded with ruddy-cheeked
officers loudly singing festive choruses. Inwardly, many, no doubt, were reflecting on the loved ones they had left behind in Old England. Few had any notion how soon they would be ejected from their warm havens and marched into battle once more. Even Captain Edward Cocks, the dashing but serious-minded officer of the 16th Light Dragoons who occasionally dined at Wellington's table, couldn't foresee anything but boredom when he wrote home to his brother on the last day of 1811, asking for more reading matter to be sent out. Cocks wanted Ferguson's
Lectures,
Rousseau's
Nouvelle Eloise
and some military texts, joking that “if we have a dull campaign next year as we had last I shall have time to read through the Bodleian Library.”

It was only in the little two-story house in Frenada, where Wellington and his staff plotted the latest French troop movements, that there were intimations that a great project might soon be afoot. In the last days of December, two most significant bits of intelligence were received: one, on Napoleon's orders, the Army of the North had sent most of its Imperial Guard troops back toward France, preparatory to the Russian campaign; two, the concentration of the Army of Portugal's Valencian expedition was completed and they began marching away from the Portuguese frontier on 29 December. Also in accordance with the emperor's orders, another of Marmont's divisions, under General Bonet, had gone north to assist in the operations against the guerrilla chiefs Mina and Longa.

News of this general eastward movement caused a stir in Frenada, and Wellington conferred with his chief engineer and quarter master general. The view in headquarters was that they needed at least twenty-four days to encircle Ciudad Rodrigo, batter breaches in its walls with heavy guns and storm the place. The British commander knew he could bring most of his troops into action from their cantonments along the border in just two or three days. Leaning across his maps and plotting the marches of Marmont's divisions toward Valencia with a pair of dividers, he waited patiently for them to get far enough away to guarantee him that working time.

At last, on the first day of 1812, Wellington decided that his operation to seize the border fortress was finally feasible. He knew it would be several days before Marmont even realized what was happening, at which point a good portion of his force would have marched too far away to alter the issue. The QMG department drew up detailed orders
and dispatch riders flew to the army's divisions to set the great machine he had assembled on the frontier into motion.

The Light Division headed off first, with the mission of putting a close blockade around the fortress. “During this march,” one of its young officers recorded, “a tremendous storm of sleet and snow took place. The snow froze and adhered to the horses' hooves, forming balls which raised them several inches from the ground.” The soldiers of this force then forded the Agueda in this freezing weather and marched around the town in a great encircling movement. Further upstream, heavy wagons and guns began crossing a specially built bridge, and by 8 January the fortress and its two thousand defenders were surrounded.

Any good engineer could see that the best means to approach Rodrigo was from a hill called the Great Teson, less than half a mile from its defenses. The French had assumed this high ground would not be used by the enemy's heavy guns because of the natural obstacle of the River Agueda, and added further discouragement by placing a small fort on top of the feature. An improvised bridge had taken care of the river, and on 8 January an assault by picked men of the Light Division dealt with the little redoubt atop the Teson. Up there, they could start using their guns and begin working toward the points of the fort's walls they intended to attack.

That night the infantrymen had worked away feverishly in the darkness with picks and shovels; racing against the sinking moon, they knew that at first light their trench would certainly be bombarded by the city's defenders. By the time dawn came this first parallel, six hundred yards long, was completed handsomely, with a four-foot rampart of earth-filled gabbions, and at daybreak, a furious artillery battle was joined. The French tried to knock down the parallel trench and prevent the British from putting their siege artillery into it. The attackers used their guns to try to silence the defenders and then begin the process of battering holes in the defensive walls.

At night, the British troops hacked away once more, advancing a new trench toward the city. Not only was it was cold, dirty work, with the men often standing up to their knees in muddy water, but it was also extremely dangerous. Aiming into the dark, the French began using two heavy mortars to kill the men digging their way forward. These weapons fired a great explosive shell high into the air, which if its fuse was cut to just the right length, would explode ten or twenty feet above
the diggers, cutting them to pieces with shards of metal. The British troops soon christened these mortars Big Tom and Little Tom, and when they heard the distinctive boom of a heavy mortar, a keen-eyed man would scan the night sky for sight of the fizzing fuse burning away on the shell, and his shouted warning would send the others diving into the mud. “Now was a time to cure a skulker or teach a man to work for his life,” wrote one private of the 95th Rifles engaged in this grim work. “We stuck to our work like devils, sometimes pitching ourselves on our bellies to avoid … being purged with grape or canister.”

The British move had come as a grim surprise to the French, and the fort's governor knew it was vital to get word to Marmont that he was under attack. A Spanish collaborator was finally able to slip out of the fortress with an urgent message concealed in his clothing, but patrols of Don Julian's guerrillas were so frequent that it took him days to arrive in Salamanca. It was not until 14 January that word reached Marmont himself in Valladolid. Little did he know it then, but as he issued his orders for an immediate concentration of French forces, matters in the borderlands were already moving toward their critical stage.

The progress of Wellington's excavations was such that one week after operations had begun, on 15 January, a second parallel had been thrown up much closer to the walls; only about two hundred yards away to be exact, on a small ridge called the Lesser Teson. After nights of back-breaking labor, this new trench was finally close enough to allow the battering guns to begin smashing Rodrigo's defenses. With one brigade of guns installed in this position and four more firing from the higher ridge behind them, the town's works began to crumble. All day long the booming report of twenty-six siege guns was followed moments later by the crump of the heavy ball hitting flagstones at the base of the walls. For the unfortunate French conscripts, this hail of roundshot marked a counting of the hours until their situation would become hopeless. They could feel each tremor under their feet as a twenty-four-pound ball struck home and chipped a little more of their security away.

By 19 January the Royal Artillery had opened two breaches in the wall. The larger of the two was a gap about thirty feet wide, two hundred yards from the second parallel. Not only had the topography of the Teson ridges favored this point by allowing the guns to fire down at the
base of the wall, but the harsh curve of the walls made it very difficult for the French to enfilade any infantry attacking here. Since it was important to attack such a target at several points at once in order to make sure the defenders would be unable to concentrate effectively at any one point, a lesser breach had been made about two hundred yards to the east of this great gap.

At dusk on the nineteenth, men of five British assault columns moved into position. The air was thick with trepidation, for no task was more dangerous than the storm of a breach. One sergeant watching the stormers walking down toward the second parallel pitied them, knowing their task was “the worst a soldier can undertake, for scarcely anything but death looks him in the face.” The defenders would have piles of loaded muskets stacked and ready to fire, as well as grenades, mines and other devices to cut down as many of the stormers as they could. All the same, most of the soldiers embarking on this horrific duty were volunteers driven by a reckless sense of adventure and, in some cases, ambition. In the Light Division, twice as many had offered themselves than were needed. Each man, officer and private alike, sought to beat the odds, and by mounting the breach first, distinguishing himself in the eyes of his generals. Their gamble was a desperate one, but if they succeeded and survived, a mention in dispatches by Wellington would bring promotion to a young captain and perhaps even an officer's commission for a ranker. Watching them shuffling forward, other men shouted encouragement. A ration of spirits was broken out and a band played a tune recognizable to them all as the “Storm of Paris.” As they crouched behind gabbions waiting for the signal, musket balls cracking and whining overhead, many offered up a prayer. General Craufurd spoke to his men, exorting them: “Soldiers! the eyes of your country are upon you. Be steady, be cool, be firm in the assault.”

Looking up at the defenses, the stormers could see the glow of the French linstocks burning slow matches, ready to be touched to a mine or cannon, showering them with grapeshot. Picked volunteers would be the first over the top of the trench and would lead the way to the base of the breach, a task so dangerous that these groups were called Forlorn Hopes.
*
At seven, the bell tower atop the cathedral chimed the hour
and those leading stormers broke cover and began running across the open ground. General Picton's 3rd Division was taking the main breach, Craufurd's Light Division the lesser one and three other columns were heading for other sections of the defenses with scaling ladders.