[SIZE=3]Revue d'Action Militaire: Uyuni: Tanks Clash in the Andes[/SIZE]
Article from Le Spectateur militaire.
In the frozen pre-dawn hours of March 18th, 1933, Chilean troops of the Army of Valparaíso-O'Higgins massed outside the Bolivian town of Uyuni. For the first time in the Andean War, the Bolivians were on their home ground, facing the Chilean Army as it pushed slowly through the Andes Mountains toward their objective of Potosí.
Bolivian General Felix Stiles, commander of the defending Colorados Division, faced a desperate situation. For the past four months, the First Bolivian Army, once 60,000 men strong, had been encircled and trapped in the Chilean city of Calama, slowly succumbing to a combination of starvation, dehydration, disease, and combat. The Colorados had only narrowly escaped the Calama encirclement, retreating back to the border in defiance of the ruling military junta's orders. When the Colorados had first crossed into Antofagasta in February 1932, they had numbered twelve thousand strong - the elite mountain division of the Bolivian Army. Attrition over twelve months of fighting had cut their numbers to just under five thousand men. Yet along the way they had made an impression on their Chilean enemies: General Ricardo Larrain, the chief of the Chilean Army during the Andean War, classed them as an elite unit, and commented later "the Colorados were twice as good as the other Bolivian divisions."
The seige at Calama prevented the Chilean Army from moving in force into Bolivia, but during late February and early March, General Agustín Sommermeier's "Army of Valparaíso-O'Higgins" skirted the edge of the seige and advanced up the Ferrocarril de Antofagasta a Bolivia (FCAB) railway. Cresting the Andes Mountains, the seven thousand men of Sommermeier's command came down towards the Salar de Uyuni, one of the largest salt flats in the world. On the eastern shore of the salt flats lay the railway town of Uyuni, where Bolivian High Command wished to halt the Chilean advance.
General Stiles made Uyuni his headquarters as he fell back from the Calama encirclement, and Bolivian High Command sent him what reserves they could, swelling his force to nearly eleven thousand men. The new arrivals were a source of irritation to Stiles; most had received only two to three weeks of military training, or were boys and old men; they had no modern artillery, and most carried rifles removed from service twenty to twenty-five years prior. These troops meshed poorly with the professional, battle-hardened Colorados, and Stiles organized the newcomers into the six-thousand man Reserve Brigade. But one unit impressed Stiles with their professionalism and level of equipment: the 19th Cavalry Squadron, which was equipped with sixteen carefully-hoarded SCT-1D tanks.
Armour in the Mountains
During 1932, both Chile and Bolivia used tanks in combat on the Atacama. At the end of the war, researchers discovered that Bolivia had, at the start of the war in February 1932, secretly built the largest armoured force in South America. The first tanks to arrive were surplus Fiat 3000s, the Italian-built version of the Renault FT-17, known as the first truly successful tank in history. While records are still unclear, it appears that Bolivia surreptitiously acquired between fifty and sixty Fiats from international arms dealers. The Bolivians then smuggled in dozens of Carden-Loyd tankettes, and purchased over fifty SCT-1D Scout light tanks from South Africa.
The Chilean Army, by contrast, moved more lackadaisically, acquiring a number of AT-17s (the Atlantean version of the same FT-17 base tank as the Bolivian Fiat 3000s), and a dozen Carden-Loyd tankettes. Very few of these initial vehicles survived the early days of the Andean War, being squandered in counterattacks on strong Bolivian positions. More AT-17s arrived from Atlantis, however, as did sixteen highly modern machine-gun armed AT-32 1A2s and a pair of 37mm-armed AT-32 1A3s.
Both Bolivia and Chile discovered, to their disgust, that the operational use of their Fiat 3000s and AT-17s was limited in the Andes. The motors struggled to get enough oxygen to function, and the low engine power reduced speed to walking pace... or less. At points, the Chilean Army resorted to desperation measures, putting their AT-17s on flatbed trailers, hitching together three artillery tractors, and literally carting their tanks to the battlefield. The Carden-Loyd tankettes were much more successful, having enough reserve power to operate in the high altitude environment. But Bolivia found their South African SCT-1D tanks to be the cream of the crop. Even though the Scouts only carried a 15mm machine gun, they had the best balance of power, reliability, speed, and protection of any of the Bolivian tanks. The Chileans, less impressed, dubbed the SCT-1D's "Scoots".
On the Chilean side, the AT-17s soldiered on until AT-32s arrived from Atlantis. These machine-gun armed tanks were Chile's closest approximation to the Bolivian SCT-1Ds, but were significantly heavier, at fourteen tons. Nevertheless, they had a high power-to-weight ratio and good protection, usually shrugging off the improvised Bolivian antitank weapons. More importantly, they were far more reliable than the well-used AT-17s. (In the early days of the Bolivian invasion, a Chilean counterattack led by AT-17s fell apart when seven of the participating twelve tanks broke down. The tanks had to be abandoned, and were captured and repaired by the Bolivian Army.) No AT-32 was ever permanently lost to mechanical failures, although one was irreparably damaged when it was driven off a small cliff into a river. The Chilean Army also acquired a pair of AT-32 1A3 tanks, armed with 37mm antitank guns. These two tanks, nicknamed "Razon" and "Fuerza" (Reason and Force), were handed over to the 10th Cavalry Regiment, a battalion-sized unit which served as the reconnaissance force of the Army of Valparaíso-O'Higgins.
Through the course of 1932, Bolivia lost most of their Fiat 3000s, Carden Loyds, and SCT-1Ds in combat during the Battle of the Atacama. On only one occasion during this time did Chilean and Bolivian tanks meet each other in combat. On September 20th, outside the city of Antofagasta, a quartet of Chilean AT-17s encountered six Bolivian Fiat 3000s, and launched into a ten minute artillery duel. The Bolivians knocked out two AT-17s without loss before the Chileans withdrew, but not before calling in naval gunfire support. A dozen 20.3cm shells knocked out all six Bolivian tanks, ending the first tank-versus-tank battle of the Andean War. Chilean and Bolivian tanks would not meet again until the Battle of Uyuni, when the Bolivians committed their last SCT-1Ds and Carden-Loyds to the fight.
The Battle of Uyuni
The Chilean commander, General Sommermeier, wanted to seize the railway town of Uyuni before Stiles' Colorados Division could erect more formidable defenses. At Uyuni, the FCAB split, with one track heading northward toward La Paz, and another heading northeast to Potosí. The capture of Uyuni would sever the last major thoroughfare through southwestern Bolivia. General Stiles' goal, stated in an address to his troops on March 11th, was to "stop the Chilean invader cold, push him back, and defeat him utterly." More pessimistically, in communications to Bolivian High Command, Stiles observed "In three weeks time I will be forced to fall back into the mountains behind me to defend the road to Potosi."
Bolivian High Command, led by junta leader and effective president Juan de la Juanquino, refused to hear of retreat, and issued Stiles their last remaining armoured reserves, consisting of sixteen SCT-1D scout tanks, and twelve Carden-Loyd tankettes. At Uyuni, the tanks would be able to use the favorable terrain to their best advantage: although the altitude was high, the ground was flat and hard, which would hinder Chilean infantry's attempts to dig in for shelter from the tanks. Stiles hoped the open terrain, with minimal ground cover, would prevent Chilean infantry from employing their traditional anti-tank tactics. Carefully-organized infantry teams would attack Bolivian tanks, and their accompanying infantry, with machine guns and rifle grenades, forcing the Bolivian tankers to "button up" for safety. With the tankers' visibility thus hindered, Chilean soldiers would dash forward carrying explosive charges or gasoline bombs, which they would throw under the tracks or onto the engine compartment. The most popular type of anti-tank charge was the "Spider", a 4kg charge with eight hooked arms splayed out to catch, like grappling hooks, on the target tank. Mortars and rifle grenades were also favorite tools of the Chileans.
Sommermeier's Army of Valparaíso-O'Higgins was smaller than the defending Bolivian Army, boasting seven thousand men - four thousand less than their opponents. However, the Chileans had significant advantages. The Army of Valparaíso-O'Higgins had been raised the previous year from new recruits, with a healthy leavening of combat veterans and officers to season them. However, unlike the Bolivian recruits being rushed to join Stiles at Uyuni, Chilean recruits were in a different class: they had received a full four months of training, while the Bolivians had only a few weeks. The infantry carried new rifles, wore fresh uniforms with ponchos made of alpaca wool, and topped everything off with new stahlhelms. The Army of Valparaíso-O'Higgins had six mortar companies with brand-new 81mm Brandt mortars, and two artillery batteries with German 105mm guns. The supply troops were mostly motorized; the Chilean soldiers received three times as many calories per day as their Bolivian counterparts, and received medical attention on an almost daily basis. In the high altitudes, soldiers who had difficulty breathing the thin air received caramelized candies made from cocoa leaves in order to help with altitude sickness. When a Chilean battalion suffered significant casualties in combat, it was quickly returned to the reserve, where the casualties were made good with new recruits, and the unit was rested. In a war fought in a wilderness, the Chileans organized their tactical forces on the battalion level, while the Bolivians tried to control all tactical and strategic maneuvers at the division level. The inevitable result was that the Chilean infantry remained fresh and combat-ready, able to march further, fight harder, and take fewer casualties than their Bolivian opponents.
On the afternoon of March 16th, Sommermeier's lead battalions opened the attack on Uyuni, striking out at a misplaced Bolivian infantry battalion on the Bolivian southeast flank. Three Chilean alpine battalions attacked from the west and south, catching the Bolivians in a closing vice. The Bolivians, inexperienced troops of the Reserve Brigade, immediately fled, suffering high casualties during their withdrawal, which threatened to instill panic in neighboring Reserve Brigade troops. To shore up the line, Stiles dispatched one battalion from his tough, unflappable Colorados, supported by the Bolivian armour. By the time they arrived, the Chileans had already withdrawn. They suffered twenty killed and thirty-nine wounded in exchange for over two hundred Bolivians killed or made captive.
As the sun set that evening, two more Chilean infantry battalions came up and launched a harassing attack on the northern end of the Bolivian defenses, supported heavily by the Chilean artillery. Both sides held their positions through the night, but the Chilean artillery, trained for Prussian precision, caused further Bolivian casualties. Stiles decided to bring his elites into play, planning a dawn counterattack on the forward-most Chilean troops, supported by the tankettes. While the Reserve Brigade manned the line, the main force of the Colorados fixed bayonets and charged. They succeeded in dislodging Sommermeier's two battalions, but the Chileans suffered fewer casualties.
As the Chileans withdrew to the north on the morning of March 17th, Sommermeier's active force attacked again on the southeastern end of the line. Facing more inexperienced troops of the Reserve Brigade, the Chilean 32nd and 35th Cazadores Battalions briefly broke the Bolivian line. Stiles sent his tanks to respond. Due to mechanical delays, only four set out; but they stopped the attack. The battlefield then fell silent for the afternoon as Sommermeier evaluated his foe's dispositions.
March 18th
As darkness fell on the evening of the 17th, Sommermeier decided to go forward with a pre-dawn attack on the Bolivian defenders. He would first strike out with the 10th Cavalry Regiment in order to conduct a reconnaissance-in-force on the southern end of the Bolivian line, where he believed Stiles had positioned many of his weakest units.
The seven hundred man strong 10th Cavalry Regiment had two AT-32 1A3 tanks and a dozen Carden-Loyd tankettes - half of them war captures - scattered between their three squadrons. But these vehicles would be used as a follow-on to the initial attack, made be a dismounted squadron of cavalry, attempting to infiltrate the Bolivian lines in the fashion of the German sturmtruppen. Chilean cavalrymen moved forward at 0500 hours, using their curved corvos on the Bolivian sentries. When the Bolivians finally raised the alarm at 0550 hours, the infiltrators were already in their midst, armed with submachine guns. A panic started, and the Chilean commander fired two flares to summon his reinforcements. The rest of the 10th Cavalry moved forward, led by their armoured vehicles.
Stiles, discerning that the southern end of his line was in jeapordy, sent his "fire brigade" - the SCT-1D tanks and the attendant tankettes, supported by his most mobile troops. For the second time in the war, Bolivian and Chilean tanks came into each others' gunsights.
Sergeant Rafael Para, the commander of the AT-32 1A3 tank Razon, received his first clue about the Bolivian tanks through the radio. A cavalry scout car, equipped with a radio, reported to the commander on the regimental radio-net. The commander of the 10th Cavalry, a Valparaiso native by the name of Major Antonio Sanmartin, barked out the order, "Enemy tanks! Let's hit them!" Sanmartin called for the regimental mortars to launch parachute flares, and moments later, Sergeant Para spotted a tankette. He quickly gave directions to his three fellow crewmen, and the 37mm gun fired. "The first shot went over," Para recalled later. "I overestimated the range. We reloaded quickly, and I kept the tankette in my crosshairs. He heard the shell whistle over, and stopped in confusion - and then I saw a crewman poke his head up. Sergio [the gunner] then announced 'Loaded!' and I replied, 'Fire!' The shot was perfect."
In the gray light of the dawn, the Bolivians believed their lead tankette had run afoul of a Chilean anti-tank team, and spread out, calling on their infantry to protect them. Para chose another target, a SCT-1D, as it drove past the burning Carden-Loyd, clearly silhouetted against the flames. "I ordered 'Turret track five left! Load! Range two hundred!' Sergio shouted his affirmation, then fired. The shell hit the hull just to the right of the driver, and penetrated the armour. Then Fuerza opened fire."
To the northwest of Sergeant Para's tank, Lieutenant Paul Simpson, the commander of Fuerza, had his own target in sight, firing a 37mm shell into another SCT-1D tank, without apparent effect. Simpson ordered a second round fired, then a third, thinking he'd missed. "But then there was a little flash of flame from inside the turret," Simpson said. "The tank kept going, but there wasn't anyone left alive inside."
Clattering forward in the growing light, the two Chilean AT-32s spotted more Bolivian tanks, spread out over the desert; and the Bolivians spotted them. "I had barely put the hatch down when there was a sound like very loud hail against the front of the turret," Simpson said. "One of the Scoots had opened fire on me with his 15mm machine gun. Little flakes of metal and dust cascaded off the inside of the turret; only my goggles kept them out of my eyes. I turned the turret about and we fired a 37mm shell at the shooter. Immediately, the bullets stopped."
A similar situation plaged Sergeant Para's Razon. A machine-gun bullet entered through the driver's vision-slit, then bounced off the rear wall of the driver's compartment and hit the back of the driver's helmet, stunning him. Razon continued clattering forward, the driver momentarily heedless of Para's calls to halt. Despite the low speed, Para and his gunner were unable to keep the gun on target for long enough to shoot. Lieutenant Simpson followed the unplanned advance in Fuerza, stopping every twenty seconds in order to fire. In this fashion, Simpson's crew killed two more Scoots. "About that time, the Bolivians must have decided we were invincible," Simpson said. "They kept shooting with their machine guns, but they put their tanks into reverse and withdrew so fast that two of them backed into each other. Then Razon finally stopped, about a hundred meters from the two collided tanks, and we fired at them until they both blew up."
As the Bolivian tanks burned or retreated, the reserve infantry they'd come to protect completed their panic, and fled in total disarray. Major Sanmartin later opined, "On a different day, with more armour and mechanized infantry, it would have been a golden opportunity to run them down. We could have collapsed the southern end of the defense line. But the infantry was too busy with the Colorados to the north, and we had too little strength or mobility to exploit our success."
Gathering up the dismounted cavalry behind him, Lieutenant Simpson still tried to pursue the Bolivian armor. Para's tank killed another Scoot and a tankette, while Simpson targetted two more tanks. The first tank lost a track as a result of Simpson's 37mm hit, and got stuck, Switching targets, Simpson disabled another SCT-1D before returning to finish off the cripple. At last, low on ammunition, the two AT-32s withdrew.
Aftermath
The tank duel on March 19th was not decisive in winning the Battle of Uyuni. The 10th Cavalry Regiment lacked the manpower and the mechanized mobility to route the Reserve Brigade, of which three whole battalions had panicked and fled. General Stiles reacted by sending the Reserve Brigade to guard the railway toward Potosí, and shortened his battle-lines, leaving only his elite Colorados in the line of fire.
The two tank forces, small as they were, did not enounter each other again. In the post-battle analysis, the Chilean Army determined that Lieutenant Simpson's tank had destroyed seven SCT-1Ds in the space of fifteen minutes, while Sergeant Para claimed two tankettes and three tanks. Only six SCT-1Ds remained to the Bolivians; and two were destroyed later in the day by Chilean artillery. Over the next two weeks, the survivors were slowly picked off by grenade-armed Chilean anti-armour teams.
The fighting around Uyuni reached a high point on March 31st, when Sommermeier's forces finally broke the exhausted and bloodied Colorados Division and entered the devastated town of Uyuni. General Stiles, having been outmaneuvered and surrounded, surrendered the remaining twenty-five hundred men of his command. The Reserve Brigade, oddly, escaped the encirclement, marching to join the defenders of Potosí, pursued by the Chilean alpine troops of the Army of Coquimbo.