At the time Tenerife was the only port authorised to trade with the Americas and was therefore extremely important to the Spanish strategically.
The attack was a personal disaster for Nelson, for not only did he lose the battle, he also lost his right arm attempting to land on Tenerife.
If he had succeeded Tenerife would be a very different place today, the culture and language would have been British, rather than Spanish as it is today.
We have also written an excelent article about the battle of Santa Cruz 1797 for you to read.
This short video tells the story of that fateful venture for Nelson.