When Archduke Charles was appointed War Minister and President of the Hofkriegsrat in 1801, the problems of the Grenz required his immediate attention.

Joseph II's part-civilian 'canton' administration system had collapsed in 1802, requiring an instant resumption of full control by the military.

1802 pattern Pontonier/Tschaikisten sabre.

An investigative commission under Major-General Klein was instructed to make a full survey of the Frontier and consider the future of its troops. In Vienna, Charles reorganised the Hofkriegsrat into Departments Archduke Louis was appointed DirectorGeneral of the Grenz Department in 1803.

Klein reported that attempts to keep the Grenzer up to Line standard were futile, since there was insufficient time to learn the drill -- essentially, he recommended a return to light tactics to utilise their natural skills. Charles, never wholly free of 18th century military practice, ordered another commission to investi gate before acting. However, by late 1804, the nucleus of a new Frontier Code was ready.

The desperate state of the Grenz economy however couldn't wait: new cattle and other agricultural supplies were rushed to the area to avert famine in 1803.

While the threat of France exercised most minds in Vienna, Charles and some of his supporters began to become concerned about the decline of Turkey. Whilst this relieved pressure on the Grenz, the resulting vacuum raised the spectre of Russian expansion into the Balkans. The potential spread of revolutionary ideas from the new Italian republics to the newly-acquired Venetian possessions was also of particular concern. Later, France made peace with Turkey and with the accession of the new Tsar, Alexander I, Franco-Russian relations warmed -- Austria looked completely isolated.

In February 1804, the whole Balkan area suddenly became very unstable, as the Serbs within the Turkish Empire rebelled against the local Pashalik, (Governor), under Petrovic, (later known as Karageorges or 'Black George'). While Petrovic sought help from Austria, (often provided in previous revolts), even offering to place Serbia under Austrian rule as a separate unit of the Grenz, other Serbs were not of the same mind.

The Serbian Orthodox Archbishop, Stratimirovics, who had led Serbian pressure for control of the Banat within the Habsburg empire, now wrote secretly to Tsar Alexander, asking him to establish a protectorate over all Serbs, including all those in the Banat and southern Hungary, as well as in Serbia and Bosnia. [25]

For once, Austria realised the need to maintain the Ottomans' control and declined to help. Despite their differences, both Croats and Serbs were unhappy with the government's refusal and joined in covert smuggling operations to aid their ethnic relations.

Archduke Charles himself favoured limited intervention to seize the great fortress of Belgrade, [26] but the imminent war with France meant that good relations with Russia had to be maintained and resources for other action were not available. In a prophetic comment on the nature of the long-term threats to Austria's interests, which still has its echoes today, Charles wrote on 23rd April 1804, "Russia has an interest in making Austria powerless, so that the Tsar can more easily engulf the Turkish Sultan" - his solution, to ally with France, was ignored. [27]

With the major powers distracted, Turkey soon gained the upper hand in Serbia and Ottoman troops even raided the Banal District in 1804. The problem was so great that the Szluin battalions from Karlstadt had to be rushed to the area to support the local Grenzer, and later, in accordance with the 1782 standing instructions, reprisal raids were made, but nothing else was done.

Archduke Charles was toppled from his government posts by Court intrigues early in 1805 and General Mack, the Emperor's Chief-of-Staff, began his own army reforms. Like the Line regiments, the 17 Grenzer regiments were supposed to be divided into four battalions each, made up of four companies -- artillery detachments had already been reduced to about 50 men per regiment. Archduke Charles realised the danger of this very late reorganisation and stayed with the old formations during his 1805 Italian campaign.

In the war of 1805, the Grenzer were able to field about 48,000 men, but they were clearly losing their old capabilities and rarely fought as skirmishers. Their lack of formal training obliged them to fight in column in most situations. General Schoenhals, who served in the Ulm campaign as a junior officer said they (Transylvanian and Slavonian units) had been mustered too quickly, lacked training, boots, uniforms and serviceable muskets, "Every report complained about their unreliability and lack of courage in battle".

Just prior to the war, Napoleon's spy Schulmeister had been more flattering: 'The Grenzer battalions are stronger than the Austrian battalions and their soldiers give a more military and healthy impression'. [28] In Italy, where the more broken terrain suited them better, the Grenzer units fought well, although they likewise lacked jackets and trousers, many marching barefoot. [29] They formed much of the rearguard of Charles' retreating army and took heavy losses from Massena's men.

As the two armies moved out of Italy towards Hungary, a French division under Serras advanced deep into Civil and Grenz Croatia - all they faced were the LandesDefension Divisions, who put up little resistance. However, the campaign at already been decided on 2nd December at Austerlitz.