King Phillip Was Fighting against Protestant Rebels in The Netherlands And after some time Elizabeth gave in to her protestant advisors. So she sent a small army of English troops to help the Rebels.
At the beginning of Elizabeth's reign she was very tolerant towards Catholics. But because of the risk of assassination plots she had to become stricter. Elizabeth Then Annoyed the Catholics by making presence to the Church of England compulsory. She Put up the fine for not going to the protestant church from 5p to 5£ which in those days was a lot of money. The fine for going To Catholic Church was 66 £ (a huge amount of Money). Sometimes if Catholic priests were caught, they would be executed.
England had also joined the 80 years war on the side of the united provinces against The Spainish.
Further More Spain Also Believed that Elizabeth Was illegitimate. under Catholic faith Henry VIII, had no right to divorce His first wife, Catharine of Argon, to marry Elizabeth's mother, Meaning Elizabeth had no right to the throne.
Philip wanted a catholic ruler it could have been Mary queen of Scots, a Catholic ruler brought up...