The American War for Independence faced challenges on many fronts. First and foremost, the colonists themselves had reservations about seceding from the mother country. They were Englishmen, after all. Many also feared that the European powers had hegemonic ambitions in the New World.
The colonists particularly wanted independence on their own terms, not one clouded by the specter of Spanish or French dominance. Meanwhile, other colonists feared the unknown, and worried that their vision for freedom would be thwarted by a failure to thrive as an independent nation.
The colonists weren't the only ones with reservations. Countries like Spain saw an opportunity to weaken British dominance across the world stage. However, the Spanish felt uneasy about helping, as their own country had been ruled by kings since the Middle Ages. Would playing a part in the American war for independence encourage their own citizens to revolt against the Spanish monarchy?
Meanwhile, France didn't want to be seen as a direct ally until victory was relatively assured. The British crown was a formidable enemy, so the French needed to be cautious.
In the end, European powers like France, Spain, and the Netherlands aided the Patriot cause with arms, munitions, financial support, and military leadership. All three countries began by providing covert aid. The Dutch sent out munitions from the Caribbean island of St. Eustatius and Curaçao off the coast of Venezuela.
The French also secretly provided arms and munitions. Predominantly, French gunpowder and guns were responsible for the defeat of the British crown at the Battle of Saratoga. That military victory gained the colonists what they wanted: explicit French support for the American war for independence.
Meanwhile, the Spanish leveraged their ports in Louisiana and Cuba to aid the colonists. Spain, France, and the Netherlands all played a major part in the Patriot victory.