The Dutch Republic had been an ally of Britain since 1668. For the next century, the Dutch Republic became weaker while Britain grew in power and increased it’s colonial holdings.
By the time the American colonies declared their war of independence in 1775, the Dutch Republic had a very weak navy, a few colonies in the Caribbean and was no longer considered a significant European power.
When France joined American in the war of independence, Dutch merchants started secretly trading with the Americans and the French through the Caribbean islands.
The truth is, Dutch helped little in the American war. It was only able to help in terms of trading, offering important supplies to the French and the Americans for some time.
However, the Dutch Republic hadn’t officially declared support for America. This meant that it could not openly help America or fight on the American side. Besides, the Republic was so weak at this time that it couldn’t offer any military help in the American war.
The Dutch Republic had signed many treaties with Britain and had been a British ally since 1668. At the time of the American war of independence, the Dutch Republic had a stalemate going on. At one side, the Dutch military came under the command of the stadholder who supported Britain.
On the other side, the States General was an important Dutch political body which supported France and America. When the stadholder wanted to officially declare support for Britain, he was blocked by the States General.
And when the States General wanted to announce support for France, it was blocked by the stadholder. This game went on and as a result Dutch couldn’t directly help France or America, they didn’t help Britain either and ultimately Britain declared war on the Dutch Republic.
This war was called the Fourth Anglo-Dutch War. At first, as Dutch merchants provided trading materials and aid to the French in the Caribbean, Britain limited itself to seizing Dutch ships and avoiding them from delivering goods to enemies of Britain.
The Dutch Republic tried to find a way out of this by attempting to sign a treaty called the First League of Armed Neutrality. If the Dutch had signed this treaty, they would have become allies of other European powers such as Russia, Norway and Sweden. But before the Dutch Republic could sign the treaty, Britain declared war on the Republic in December, 1780.
The Dutch Republic was no match for Britain at the time. Britain simply used its naval supremacy to neutralise the Dutch. The Britain blockaded the Dutch ports, banning any Dutch ships from reaching seas. At this point, the Dutch navy only had 12 ships, so the main party affected by this blockade was Dutch merchants.
Britain also attacked and took control of most of the Dutch colonial holdings in West India in 1781. In India as well, Britain used the East India company ships and assets to destroy many Dutch holdings, greatly reducing Dutch colonial power in the region.