Kasteel Ammersoyen (Ammersoyen Castle) is located in the town of Ammerzoden in the Bommelerwaard region in the province of Gelderland, the Netherlands.

It is unclear when the original construction of the Castle occurred; some sources claim it was as early as the 12th century. 

However, the consensus among historians is that the Van Herlaer family completed the Castle in the 1350s. At the time of its construction, the castle was built along a branch of the River Maas. Just a few years after the construction of the castle was completed, the river was rerouted leaving the castle to be surrounded by a moat.

The castle was designed to be a defensive fortress. When it was originally constructed, it had a central courtyard, surrounded by four heavy towers on the corners. Connecting these four towers were four heavy wings, one on each side of the courtyard.

Ammersoyen Castle is a good example of the type of castle that was made famous by Count Floris V of Holland. Even though it was originally built on a river, the Van Herlaers believed that all four sides of the castle needed to be fortified.

To add to the security, the original design included a moat that ensured any attacker could only invade through the front of the fortress. Except for a brief period in the early 20th century, the castle has always been completely surrounded the moat.

The castle was built using a fixed plan, something that was quite uncommon for medieval castles. A fixed plan means that the entire castle was built as a whole, as opposed to multiple phases, which was often the case with other medieval castles.

The earliest mention of Ammerzoden, or Ambersoi as it was once known, was in the 11th century. Given that the village was built on a river with very arable lands, it was most likely just a small farming community with little importance until the creation of the Castle in the 14th century.

Today, the village is home to approximately 4000 people, and since 1999 has been part of the municipality of Maasdriel. Prior to 1999, Ammerzoden was its own municipality.

Dirk Van Herlaer completed the Castle in the 1350s. Upon his death in 1354, the Castle passed to his eldest son, Gerhard. Over the next 30 years ownership would pass through many hands within the family.

When Gerhard died, the Castle went to his brother, Arent, since Gerhard had no children to claim the Castle as part of their inheritance. When Arent died in 1384, the Castle was given to his son, Arent Hoeman. The Van Herlaer family lost control of the Castle for good during Arent Hoeman's possesion.

In the late 14th century, the province of Gelderland was controlled by Duke William of Gelder, who had a trusted friend in Arent Hoeman. In 1386 a land dispute between Gelderland and the Duchy of Brabant lead to war.

The Burgundians were aggressively trying to expand their territory at this time, and tried to take over parts of Gelderland.

Despite his close relationship with Duke William, Arent Hoeman sided with the Duchess of Brabant in 1386.

William, unsurprisingly, saw this as an act of betrayal and abruptly ended his friendship with Arent Hoeman. Just days later, William invaded Ammerzoden, capturing Arent Hoeman. Ammersoyen now belonged to Duke William.

Following the end of the war, Duke William gave the Castle to his illegitimate son in 1405. His son did not hold the Castle for long, as he sold it to Johan Van Broeckhuysen, lord of the Waardenburg, in 1424.

The Castle changed hands only by marriage for the next 400 years. In 1496, Johanna Van Broeckhuysen married Otto Van Arkel, which ended up giving the well-known and welathy Van Arkel family control of the Castle for centuries.

At the end of their rule, the Van Arkel’s had controlled the Castle for five generations.

In 1513, during the Guelderian Wars, the Habsburgs attempted to seize control of the Castle from across the River Maas, and briefly occupied the Castle. Burgundian troops, led by Count Henrick Van Nassau, occupied the Castle for a brief time in the mid 16th century.

During the siege and subsequent occupation, the Castle was moderately damaged and a large amount of personal property needed to be replaced. At this point in their rule, the Van Arkel's were still very rich, so they had the means to repair the Castle.

The Castle was again occupied for a short time in 1572, when the Spanish invaded the Netherlands.

However, the Castle was not held long by the Spanish, as Prince Willem Van Oranje and his troops were able to drive the Spanish troops out. Liberation of the Castle kept the damage inflicted by the Spanish to a minimum.

By 1590, the Castle was fully repaired. Later that year, Ammersoyen was nearly destroyed again by a fire. The Lord of the Castle at the time, Joris Van Arkel, died from injuries that he sustained during the fire.

The fire occured during the 80 years war and caused the family to have very uncertain feelings about its economic future .

It was not until the end of the 80 years war, in the middle of the 17th century, that large-scale renovations would start on the Castle.

Not long after the rebuilding was completed, King Louis XIV of France invaded the Netherlands during the Franco-Dutch War. By the time the French soldiers arrived at the Castle in 1672, the Van Arkel’s were able to regain some of their prior wealth.

Facing threat of destruction once again, the safety of Ammersoyen was bought by Thomas Van Arkel from the French commanding officer for the sum of 7000 guilders.

While this ensured the Castles safety, it left the Van Arkel’s in a severe amount of debt, so the final interior redecorating under the Van Arkel's could not be completed.

In 1693, Thomas van Arkel died with no living heirs. Ammersoyen would change owners several times over the next century. Most were very rich Dutch families with estates all over the region, who spent little time at the Castle.

The last of the families to own the Castle was the Woelmont family. The last Lord of Ammersoyen was Arthuer de Woelmont, who bought the Castle in 1856.

Over the course of the next 17 years, he sold all of the possessions of the Castle and in 1873 he sold the Castle to the Roman Catholic Church in Ammerzoden.

By 1876, the Castle was transformed into a Convent for use by the Poor Clares, becoming the second Clarisse Convent in the Netherlands.

The nuns made significant changes to the grounds when they lived in the Castle. The moat was filled-in and a chapel was built on the grounds, which is still there today.

The start of World War II led to the end to the Convent as the area was bombed heavily. Much of the Castle and grounds were destroyed during Allied bombings.

The Castle allowed the people of the town a place to seek shelter during the War, although by the end of the War, not much of the Castle was left standing.

After the war, a local businessman used the Castle as a factory that produced washing machines.

In 1957, the Friends of Gelderland Castles Foundation bought the Castle and made extensive repairs.

Over the course of the next 16 years, they were able to restore the Castle to its original medieval construction, undoing many of the structural changes that had taken place over the centuries.

While this sounds like a difficult job, many of the changes that had taken place were actually just covered up by plaster and bricks, so recovering the original layout was not difficult.

The restoration included original size and height of rooms, reconstructed chimneys, and moved staircases.

Numerous artifacts from Ammersoyen's history were found when the filled in moat was dug out. Among the pieces found were fragments of pottery, stoneware, glass, silver, bronze, and tin. These artifacts are now on display in the Castles attic.

The Castle and grounds were opened to the public and fully restored by 1976. Until 1999, Ammersoyen was used as an official town hall and meeting place for the local municipality, in addition to being a tourist attraction.

After the Ammerzoden municipality ceased to exist in 1999, the meetings were moved from the castle.