The Treaty of Helmgart was signed in 2500 securing the neutrality and independence of Marienburg. It is noteworthy for two things: Marienburg was not a signatory, although an elven representative was; and it was broken two years later by Bretonnia, causing a shift in local political relationships. Of course, we should expect little better from the Bretonni!
The premise behind the treaty was simple: Bretonnia and The Empire both harboured ambitions over the city, but were far more worried about the other obtaining it than their own territorial desires. Equally, both had other border worries at the time, coupled with certain internal concerns, and desired to stabilise this particular disagreement to mutual benefit. Marienburg itself was left out of the negotiations, although it is possible that they were aware of them, perhaps even behind them. However, this is less likely given that an elf signature was also penned to the treaty. It is still uncertain exactly what the elves sought to gain from such a treaty, particularly one without the consent of the city's human authorities. However, doubt was also (later) cast on the precise nature of the authority of the signature that was made. Rumours later circulated that this had been a wood elf, rather than a sea elf, party to the treaty - which seems even more bizarre.
The Treaty itself was technically broken in 2502, when Bretonnia appeared to make military moves against the city state. These were officially described as military manoeuvres against local anti-Royalist forces, but were seen elsewhere as a clear test of strength. Marienburg itself proved its expected defensive frailties, when much of its mercenary defence force deserted claiming pay and conditions breaches to their contracts. At the same time, a sea elf fleet materialised off the coast and local Sigmarian militias proved far more efficient at deployment than had been suspected. When Empire merchants arrived along the Reik with their bodyguards, including much of the Carroburg levy and local Imperialist army units, the Bretonnians declared that their rebels had been defeated and retreated. The action was later officially blamed upon 'the rash ambitions of a rogue general who had spent too long patrolling the desolate Marches of Couronne'. Given the politics of Bretonnia, it is perhaps true - but was not accepted as such by anyone else.
This Bretonnian skulduggery resulted in Marienburg moving back towards the Imperialist fold, or at least away from their vocalised anti-Empire rhetoric. Certain benefits were granted to the Sigmarian sects in the city and state. However, distrust between the human political rulers and the sea elf princes were reinforced over their part in the treaty. Marienburg also allegedly supported Imperialist investment in a small river navy based in Carroburg through the cancellation of certain debts contingent upon its construction and operation. However, normal relations were resumed when the Imperialists armed their boats with small cannon and even created a floating gun platform since Marienburg regarded these more as siege weapons than a fast defence force (to be used in their interests). The Empire refuted this, arguing that a modern field force needed artillery and that cannon were a primary deterrent against a force of heavy cavalry, such as that which would be likely fielded by Bretonnia.
I suppose that we should mention that the Annals of the Kingdom of Bretonnia describe the event as Bretonnia's attempt to protect the independent Wasteland from the rapacious armies of the Graf of Middenheim. Their Chronicler claims to provide what he described in published correspondence as "the correct and impartial historical account". However, an investigation by the Senate of the University of Altdorf found this account "riddled with inaccuracies and polemical irrelevancies".
One casualty of the skirmish was General Johann von Foodee, the Graf of Middenheim's then mercenary captain, who died in a tragic accident some days after the furore when he was said to have fallen upon his sword.
The Carroburg fleet is pictured below, in what is a rather poor quality engineering manuscript. Of particular interest is the fact that the crews are facing both ways and rowing against each other. This might be a stylised representation, or a joke by the Bretonnian engineer responsible for the sketches.
It is unlikely that the cannon would be fired from the raft and the Empire argument does seem plausible. Indeed, it later emerged that most of the cannon on the ships were wooden fakes and that much of the money loaned by the Marienburg Directorate had been spent on re-paying other loans - owed to a cartel of Bretonnian-based gnomes!
