Hellburners

Hellburners (Dutch: hellebranders; brander is Dutch for "burner") were specialised fireships used in the Siege of Antwerp (1584-1585) during the Eighty Years' War between the Dutch rebels and the Habsburgs. They were floating bombs, also called "Antwerp Fire", and did immense damage to the Spanish besiegers. Hellburners have been described as an early form of weapons of mass destruction.

The hellburners were constructed by the Italian engineer Federigo Giambelli, who had been hired and subsidised by Elizabeth I of England, unofficially supporting the rebels, to assist the city. In the winter of 1585 Antwerp was besieged by the army of Alexander Farnese, the commander of the Habsburg forces in the Spanish Netherlands, who had constructed an eight-hundred-metre-long ship bridge over the River Scheldt near Kalloo between Antwerp and the sea, to starve the population by blockade; it had been completed on 25 February. To supply the city it was imperative to destroy the ship bridge.

Giambelli first proposed to use three medium-sized merchantmen, the Oranje, Post and Gulden Leeuw, but this was refused, only two smaller vessels being made available: the Fortuyn ("Fortune") and Hoop ("Hope") of about seventy tons. The innovative part of the project consisted in the Hoop employing a fuse consisting of a combined clockwork and flintlock mechanism provided by an Antwerp watchmaker, Bory; the Fortuyn used a delayed fuse mechanism.

To ensure destruction, very large charges were used. To intensify and channel the explosion an oblong "fire chamber" was constructed on each ship, a metre in diameter. The bay was fitted with a brick floor, a foot thick and five metres wide; the walls of the chamber were five feet thick; the roof consisted of old tombstones, stacked vertically and sealed with lead. The chambers with a length of twelve metres were each filled with a charge of about 7000 pounds of high quality corned gunpowder. On top of the chambers a mixture of rocks and iron shards and other objects was placed, again covered in slabs; the spaces next to the chambers were likewise filled. The whole was covered with a conventional wooden deck.

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Wikipedia