Mexico was very much an active posting for the Austrians, Poles and Hungarians of the Austrian Legion, and for example, most families were left back home in Europe. When the wife and children of Edmund, Graf Wickenburg, arrived a fellow officer wrote "What a decision for a woman with her children! Such a long journey to lead a Mexican officer's life!", even though they were based in the capital, Mexico city. The countryside was full of bandits and all transport required strong escort.
The usual pattern was for a few rifle companies with cavalry support, and Mexican auxiliaries, to be launched as flying columns against insurgent targets. The cavalry were sometimes sent out by themselves as independent squadrons, such as an Uhlan (lancer) squadron under Ernst Graf Fünfkirchen, who mainly operated against local gangs in the countryside, but unfortunately there is little record of these "police" actions, sometimes just the name of a town in the official biographies of officers.
For example, the official biography for Karl Manussi von Montesole, an Unterlieutenant 1st class in the Jagers at this time, lists the following for 1865;
“Tezuitlan, Zacapoaxtla, Azala, Hochiapulca, las Lomas, Hachiapulca, Elxochito, Comaltepec, la Hoya, Tetela d'Oro, Zantla, dos Cerros and the storming of Tlapacoyan”
and for 1866:
"Apolecca, several smaller battles against Porfirio Diaz, Tehuacan and Hnajuapan”
The first major offensive was launched against the Sierra del Norte from July 1865. The forces here were mainly indigenous Cuatecomacos under General Francisco Lucas. They had already resisted an earlier French assault, but Thun took care to recruit local forces from the plains, especially cavalry. His artillery, under Weinhara, were not ready at the start, but followed on and soon made their presence felt. This was a war of ambush and the storming of towns, the artillery were useful but suffered heavily and one consequence was the urgent training of every gunner in use of a rifle, as previously gunners in the Austrian army were unarmed, and helpless in an ambush.
Thun's campaign was energetically conducted, with Republican troops attacked at every opportunity. The first major target was the heavily defended town of Teziutlan, garrisoned by about 1,000 men, a third of them cavalry. Thun at this point had neither Austrian cavalry or, crucially, artillery, but he sent 3 companies of Jagers, and about 75 Mexican cavalry. Somehow they managed to reach the town undetected after a night march and at dawn they attacked, the 6th company under Captain Hassinger von Perote reaching and taking the market place. Lietenant Manussi von Montesole won the Bronze Military medal, but sadly Hassinger died from his wounds. The survivors dug in and repelled a counter attack a few days later. This first victory made news in Mexico and in far off Austria, the Emperor himself saying that "if I lived a long time there would not be good day, as the news of this beautiful affair,"
The Sierra del Norte
From a secure base at Tezuitlan in July Thun struck out in all directions. Huahuaxtla was taken without a fight, and a stand at the bridge at Apulco was broken by two mountain guns (now arrived) and a flank attack by Mexican cavalry. Another battle group with an infantry company and Mexican lancers took Tetela. Tlapacoyan repelled one attack, but was stormed at bayonet point on November 22nd and the defenders scattered leaving many rifles and ammunition behind. Unterlieutenant Karl Manussi von Montesole of the Jagers received the Order of our beloved Madonna of Guadalupe for his part in this.
It hadn´t gone all their own way however. On 17th July, Captain Graf Karl Kurtzrock -Wellingbuttel led 3 platoons of his 3rd lancers (64 mounted and 55 on foot) and some 115 Mexican troops against the mountain village of Ahuacatlan. Presumably the lancers on foot borrowed rifles as there were only 16 carbines per squadron, a major deficiency in this type of op. Attacked by 3 x their numbers they were forced into the church were they resisted for several hours before their captain was killed and the remaining 28 survivors, most of whom were severely wounded, surrendered. Fortunately for them a squadron of lancers under Oberleutnant Wolf-Metternich, having made a forced march, managed to free them a few days later.
Hussars in the Sierra de Huahtla
In Tehuacan in the the Sierra de Huahutla he received news from local sympathisers that there was a concentration of the enemy at Mazatlan and he set out with a small force of 15 hussars and 26 native infantry to disperse them. He set out at noon for Teotitlan where he discussed the operation with a local official, Luis Rosa, who gave him valuable advice on the terrain, and arranged some indian scouts. The enemy were over 200 strong, and virtually inaccessible in the mountains, but in true hussar style they decided to attack. It all depended on surprise.
They set off at night, at 9pm, on a "very arduous" march, up into the hills through dense forest and narrow clefts in the rock, so tortuous that much of the time they had to lead their horses by hand. At midnight they met two Indian scouts, who confirmed that the enemy were still unaware of their presence, so they carried on until at 6am they reached Mazatlan, where they stopped to rest the men and horses. Eventually they reached a spot below the ridge where they knew the enemy to be. Leading the horses along a circuitous path through bushes the hussars timed their attack to match the arrival of the infantry who marched straight up "at astonishing speed". At the summit the hussars and sentries saw each other at the same time and all hell broke loose, the sentries screaming "los sombreritos, los húngaros" - "the little hats, the Hungarians".
Galloping forward to survey the situation the commander saw how strong the position was, and that only an immediate attack stood any chance of success. The hussars charged straight at the infantry at full gallop, jumping a fortification ditch, and smashing the firing line that was starting to form so the Republicans routed, and it turned into a "witch hunt". The hussars were joined by their infantry and despite their exhaustion after the overnight march, many enemy were captured or driven into the the heights of Huahutla. All the enemy´s equipment and leaders were captured except one, the chief, who was attacked by the hussar commander at sword point and unhorsed, but still escaped.
Santa Gertrudis and the end of the Adventure
Nonetheless, during 1866 the troops became progressively more disheartened. There was a strong feeling that they should have been back in Austria, defending the homeland in the disastrous war with Prussia. Republican forces were better armed, and French withdraws in the face of US and Prussian pressure damaged morale still further.
As well, their Mexican allies in the Imperial army, who had never been very reliable, were now openly defecting to the enemy, most disasterously at Santa Gertrudis on June 14th. Two infantry companies and two guns had been ordered to escort a wagon train from the port of Matamoros to Monterey, together with 1,000 Mexicans under General Olivera. They were shadowed by 2,000 Republicans under Escobedo, and when the moment was right he attacked with his whole force. Olivera bolted, but the Austrians, who were leading the column, made a stand using the wagons as cover, and drove off the first attack, including a counter charge with bayonets. What happened next is disputed, but Austrian accounts claim that Olivera's Mexicans defected and attacked them from behind. Virtually all the Austrians present were killed in the fighting or captured and executed.
Things came to a head when they heard they were to be placed under the command of a Mexican general, Marquez. They protested and in December 1866 the legion was disbanded – most went home to Austria.