Background to forts of the Spice Islands

Local fortifications existed in the Spice Islands prior to Europeans arriving, but these were generally earth walled/ timber palisaded structures of limited effectiveness and very vulnerable to modern artillery.


The first colonial fortification, Kastella started by the Portuguese on Ternate in 1522, was initially constructed to a semi-medieval design with a central tower and high curtain walls. Two elements it’s subsequent improvements did introduce to the Spice Islands, however, were flanking fire from towers protruding beyond the wall-line, and parapet-mounted  breech-loading swivel guns which could inflict heavy casualties on attackers seeking to escalade the walls.

The capture of Constantinople by the Ottomans in 1453 had been a turning point in fortification design, heralding the arrival of heavy cannon in siege warfare. The high thin walls and round towers of medieval defensive works – largely concerned with preventing escalades – were very vulnerable to emerging firepower. Not only were such walls insufficiently robust to absorb bombardment, but the walls themselves were too slender to accommodate heavy guns to counter the attackers weapons.

While initially only partially effective, Kastella evolved over time – with Portuguese, Ternatean and Spanish modifications – into a very powerful and extensive fortress, declared by a Dutch commander imprisoned there in 1610 as “invincible”. Other equivalent fortresses were Victoria at Ambon, Orange on Ternate, and Nassau and Belgica on Banda.

Certainly local armies struggled to overcome well-armed and properly manned European fortifications from the 1520’s on. Apart from the surrender of Kastella by the Portuguese to Ternate’s Sultan in 1575 – after a five year siege – the only other substantial work to be successfully stormed by local forces was Fort Duurstede on Saparua near Ambon in 1817.


The development of angled bastions, first demonstrated in the region in a simple manner with the Portuguese Fort Victoria on Ambon in 1576 gave defenders the ability to sweep the wall approaches, and allowed no “dead” ground around the fort perimeter. These design elements combined with bastion-mounted medium guns and parapet-mounted quick reloading swivel guns no doubt made it difficult for attackers to motivate their men to close with the walls.

The Dutch, who commenced fort building in the Spice Islands in 1607 with their headquarters at Malayo on Ternate (later Fort Orange), were experts at defensive constructions after generations of such warfare with the Spanish in their own country. They eventually built the largest number of fortifications throughout the islands.

The standard template for Dutch forts was the quadrilateral with angled bastions at each corner, and such works – of varying sizes – were built at Malayo (Fort Orange), Tacome (Fort Willemstadt), Banda (Forts Nassau, Hollandia, Concordia & Belgica), Makian (Fort Mauritius) and Tidore (Fort Mareico). Ignoring smaller forts, only pentagonal Fort Revenge on Ai, in the Banda’s, and the later modifications to both Fort Victoria and Fort Belgica departed from this theme.


In comparison to contemporary European forts, Spice Islands examples were generally less sophisticated, less extensive and less well-armed. In the early seventeenth century, forts in the region probably relied on a mix of sakers (9 pounders) and demi-culverins (6 pounders) with perhaps some full-culverins (18 pounders) for anti-shipping work. Other smaller breech-loaders were swivel mounted on the walls for anti-personnel use. These crew-served weapons were supported by individual arms including the muzzle loading matchlock arquebus and an assortment of other edged and pointed weapons.

Today, ruins exist of around 40 Spice Islands Forts, ranging from pre-European hill forts to Japanese WWII pillboxes. In the following pages we list the main colonial forts, some no more than scattered blocks and foundation outlines; others magnificent and restored, standing proud and enduring against monsoons and humidity and blasting heat.