In which year did Spain enter the Revolutionary War?

Spain officially entered the Revolutionary War in 1779 when it declared war on Great Britain. This entry into the conflict was a significant event, as Spain sought to weaken British colonial power and support the American colonies indirectly by providing resources and assistance. Although Spain had been supportive of the American cause prior to its official entry—providing funds and supplies—1779 marked the formal initiation of hostilities against Britain.

It is important to distinguish that Spain's involvement was not through direct military action alongside the American forces but rather through its own agenda of countering British influence in the Americas and reclaiming territories lost to Britain. Therefore, 1779 is correctly recognized as the year when Spain fully committed to the war effort against the British.