Background
King Philip II of Spain was the most powerful and (seemingly) wealthy man in Europe in the latter half of the 16th century. His territories in the New World brought him enormous wealth, though the expense of administering that far-flung empire meant that Spain was heavily in debt to foreign bankers.

England, by comparison, was a relatively small nation, and not a particularly powerful or wealthy one. Why then would Philip spend the money to assemble the largest - and most expensive - naval force ever seen against his island foe?

English ship in action against the Spanish Armada
An English ship in action
against the Spanish Armada
The answer has many parts. In his youth, Philip was married to his fellow Catholic, Mary, Queen of England. He was not king, indeed the only way the English Parliament would countenance the marriage was if Philip was expressly forbidden from ruling.

He was, rather, Mary's consort, a duty he fulfilled with underwhelming enthusiasm. Philip never cared for Mary, indeed, he said while on his way to his marriage, "I am going to a crusade, not to a marriage feast". He was fueled by a religious desire to father a Catholic heir who would keep England within the Roman Catholic sphere. Mary, by now a middle-aged spinster, certainly did care for her new husband, and even managed to convince herself that she was pregnant at one point, but it was not to be.

When Mary died in 1558 her very Protestant sister Elizabeth came to the throne. Philip was unwilling to let his precarious grasp on England slip away completely; he proposed marriage to Elizabeth.

Elizabeth was a master at procrastination, and playing the game of politics. She kept communication open with Philip, and protested her friendship, all the while encouraging English pirates like Hawkins and Drake to seize Spanish ships and goods in the West Indies. Drake was dubbed by the Spanish "the Master Thief of the Unknown World".

In the 1560s Elizabeth also earned Spanish wrath by supporting Protestants in the Netherlands in their revolt against Spanish occupation.

Spain also believed, or at least found it useful to believe, that Elizabeth was illegitimate. Under Catholic principles Elizabeth's father Henry VIII had no right to divorce his first wife, Katherine of Aragon, to marry Elizabeth's mother, Anne Boleyne. Therefore Elizabeth was born out of proper wedlock, and thus had no right to the throne.

More importantly for the fervently Catholic Philip, he believed that it was his duty to lead Protestant England back to the Catholic faith - by force of necessary. He managed to get papal approval for his invasion, and a promise of money to be delivered after the Spanish had landed in England.

He also got papal permission to name the next ruler of England (by surreptitiously slipping a clause to that effect into the middle of the document of agreement with the pope). Philip planned to name his daughter Isabella as Queen of England, under his control.

The Spanish Fleet
Philip began preparing his invasion force as early as 1584. His first choice as commander was the Marquis of Santa Cruz, but when Santa Cruz died Philip ordered the Duke of Medina Sedonia to take command of the fleet. The Duke was an experienced warrior - on land. He had no naval background, and no interest in leading the Armada, as the invasion fleet came to be called. He begged to be dismissed, but Philip ignored the request.

Cadiz
Despite Spanish precautions, the English were well aware of the Spanish preparations. In a bold move that was apparently against Elizabeth's wishes, Sir Francis Drake sailed a small English fleet to Cadiz, where they surprised a large number of Spanish warships in the harbour. Drake burned and sunk a number of ships and slipped away before the Spanish could rally. Although the blow at Cadiz was more an annoyance than a major setback, the English took heart from this "singeing of the King of Spain's beard".

The Armada sets sail
By May of 1588, however, the Armada was finally ready to sail. The fleet numbered over 130 ships, making it by far the greatest naval fleet of its age. According to Spanish records, 30,493 men sailed with the Armada, the vast majority of them soldiers. A closer look, however, reveals that this "Invincible Armada" was not quite so well armed as it might seem.

Many of the Spanish vessels were converted merchant ships, better suited to carrying cargo than engaging in warfare at sea. They were broad and heavy, and could not maneuver quickly under sail.

This might not at first glance have seemed a problem to the Spanish. They did not intend to engage the English in a sea battle. The ships of the Armada were primarily troop transport. Their major task was simply to carry armed men to a designated landing point and unload them.

Naval tactics were evolving; it was still common for ships to come alongside each other and allow fighting men to engage in hand to hand combat. Advances in artillery were only beginning to allow for more complex strategies and confrontations at sea. At this stage the English were far more adept at artillery and naval tactics than the Spanish, who were regarded as the best soldiers in Europe.

The Spanish plans called for the fleet to sail up the English Channel and rendezvous off Dover with the Duke of Parma, who headed the Spanish forces in the Netherlands. This in itself presented huge problems. Communications were slow, and the logistical problems of a rendezvous at sea were immense.

Also, the Duke of Parma was a very proud man, and resented the fact that Medina Sedonia had been given command of the operation. Throughout the whole Armada affair Parma, while not openly obstructionist, did a poor job of cooperating with his titular commander, Medina Sedonia. He did not believe the enterprise could succeed, and he did the absolute minimum possible to help.

Perhaps worst of all the problems faced by the Armada was Philip himself. The king insisted on controlling the details of the Armada's mission. He issued a steady stream of commands from his palace of the Escorial, yet he seldom met with his commanders, and never allowed his experienced military leaders to evolve their own tactics. He did not listen to advice, which was a shame, for Philip had little military training and a poor grasp of naval matters. He firmly believed that God guided him, and that therefore his mission would succeed.

The English were not idle while the Spanish Armada prepared to sail. A series of signal beacons atop hills along the English and Welsh coasts were manned. When the Spanish ships were at last sighted of The Lizard on July 19, 1588, the beacons were lit, speeding the news throughout the realm. The English ships slipped out of their harbour at Plymouth and, under cover of darkness, managed to get behind the Spanish fleet.

The Battle
The Spanish sailed up the Channel in a crescent formation, with the troop transports in the centre. When the Spanish finally reached Calais, they were met by a collection of English vessels under the command of Howard. Each fleet numbered about 60 warships, but the advantage of artillery and maneuverability was with the English.

Under cover of darkness the English set fireships adrift, using the tide to carry the blazing vessels into the massed Spanish fleet. Although the Spanish were prepared for this tactic and quickly slipped anchor, there were some losses and inevitable confusion.

On Monday, July 29, the two fleets met in battle off Gravelines. The English emerged victorious, although the Spanish losses were not great; only three ships were reported sunk, one captured, and four more ran aground. Nevertheless, the Duke of Medina Sedonia determined that the Armada must return to Spain. The English blocked the Channel, so the only route open was north around the tip of Scotland, and down the coast of Ireland.

It was then that the unpredictable English weather took a hand in the proceedings. A succession of storms scattered the Spanish ships, resulting in heavy losses. By the time the tattered Armada regained Spain, it had lost half its ships and three-quarters of its men.

In England the victory was greeted as a sign of divine approval for the Protestant cause. The storms that scattered the Armada were seen as intervention by God. Services of thanks were held throughout the country, and a commemorative medal struck, with the words, "God blew and they were scattered" inscribed on it.

Note
The term "Invincible Armada" was not a Spanish one. It was a sarcastic phrase employed by later English commentators.

Related:
Henry VIII
Edward, Mary, and Elizabeth