Elizabeth was the sister in law of Philip of Spain, who had been King of England as Mary I’s Husband. However, they became rivals upon Elizabeth's ascension. There were two reasonds for this, first Philip was a devote Catholic and Elizabeth a renowned Protestant. Secondly, Philip lost the kingdom when Elizabeth became queen. Despite this war between the two nations was far from certain. Philip had a very great and powerful kingdom which was draining his finances, while Britain was a small and relatively weak power. Diplomatic relations deteriorated between the two countries for several reasons. Firstly, Elizabeth was converting England to Protestant and slowly passing laws against Catholics: they could not practise their religion or harbour a priest, for example. Elizabeth also allowed her navy to steal treasures intended for Spain and is reported to have ordered Francis Drake to harass Spanish ships. In retaliation Philip seized all British ships in Spanish harbours, annoying Elizabeth. Elizabeth also executed Mary Queen of Scots and provided support for Protestant Dutch rebels who wished to be independent from Span. Philip did not have the finance to fund the defence or control of his entire empire and feared that with England out of his control, Protestant and giving out support, he would not be able to assert his authority until they were dealt with. Elizabeth believed that although great, the Spanish did not have a fleet capable of sailing the shallow waters of the English Channel and so could not attack. England was also known for its fleet, which ironically Philip had re-organised, enlarged and modernised while he was Mary's husband.

Philip’s plan of attacking England was altered by the Pope’s strict conditions, in return for a large sum of money. The Pope wanted England returned to Catholicism, but did not want the Spanish to control it, believing Philip too powerful already. He, therefore, asked that the leader of the army attacking Britain was not Spanish, but a foreign Prince. Philip entrusted the mission to the Duke of Parma, an Italian Prince, who was also Philip’s nephew and head of certain Spanish territories. This now meant Philip’s fleet (of around 120-150 ships, but most were transport ships with food, tents and other supplies for the army) needed to convey the Duke and his 30,000 troops across the Channel. In order to reach the meeting point, the Spanish fleet had to sail very close to the English south coast and also the several failed communications between the fleet and the army meant neither knew where to meet the other. After a long and stormy journey, the Spanish fleet sailed near the English South coast and the British fleet was launched to meet them. The British fleet (approximately 30-40 warships and 80-100 smaller ones at one time) wass quickly alerted of the attack by the use of warning beacons placed along the South Coast; when the fleet was seen the first beacon was lighted, the next one then saw this one and was also lighted and so on.  The Spanish fleet, pursued by the British tred to locate a harbour along the Channel deep enough for their ships and where they could also meet the Duke’s illness stricken and vastly smaller army. The difference between the fighting styles of the Spanish and British made a huge difference. The Spanish would close in on a ship, board it and take hold; the British would use their powerful cannons to destroy the ship from a distance. With the Spanish ships in tight formation the cannons were not that effective. However, once the Spanish stopped in Calais, the British who could not allow the army, believed to be approaching fast, to join them. The, therefore, launched an attack with fire ships (the Britiah sailed ships on fire into the Spanish fleet); this pushed the undamaged Spanish ships (the majority of the fleet)close to the British fleet. With the Spanish ships nearer, the British cannons caused great damage. The wind then changed and allowed the Spanish fleet to sail north, leaving the army. The fleet then continued around Scotland and Ireland and sailed back to Spain.

Around 75% of the Spanish ships returned to Spain, although some sailors had been killed, from lack of water and food, on the return journey. Relations remained poor between Britain and Spain and they half heartedly attack each other throughout the remainder of their reigns (Elizabeth only survived Philip by 5 years). Though, they never declared war with each other and the following year turned their attentions towards the French civil war. The long lasting legacy of the affair was the creation of the belief that Britain's strong military power was her navy and that her ships were her strongest defensive force.