Passage: The 17th and 18th centuries saw more attacks on the island. On September 25, 1625, the Dutch, under the leadership of Boudewijn Hendrick (Balduino Enrico), attacked San Juan, besieging Fort San Felipe del Morro and La Fortaleza. Residents fled the city but the Spanish, led by Governor Juan de Haro, were able to repel the Dutch troops from Fort San Felipe del Morro. The fortification of San Juan continued; in 1634, Philip IV of Spain fortified Fort San Cristóbal, along with six fortresses linked by a line of sandstone walls surrounding the city. In 1702, the English assaulted the town of Arecibo, located on the north coast, west of San Juan, with no success. In 1797, the French and Spanish declared war on the United Kingdom. The British attempted again to conquer the island, attacking San Juan with an invasion force of 7,000 troops and an armada consisting of 64 warships under the command of General Ralph Abercromby. Captain General Don Ramón de Castro and his army successfully resisted the attack.Amidst the constant attacks, the first threads of Puerto Rican society emerged. A 1765 census conducted by Lt. General Alejandro O'Reilly showed a total population of 44,883, of which 5,037 (11.2%) were slaves, a low percentage compared to the other Spanish colonies in the Caribbean. In 1786 the first comprehensive history of Puerto Rico—Historia Geográfica, Civil y Política de Puerto Rico by Fray Iñigo Abbad y Lasierra—was published in Madrid, documenting the history of Puerto Rico from the time of Columbus' landing in 1493 until 1783. The book also presents a first hand account of Puerto Rican identity, including music, clothing, personality and nationality.

Question: How many troops were involved in the invasion of San Juan?
7,000