On July 1st, 1690, two armies consisting of Danish, French, Dutch, Huguenot, German, English and even Irish troops met on the banks of the River Boyne near Drogheda. Both were led by men insisting that they alone were the rightful King of England. The main force of both armies never took part in the fighting. The Battle of the Boyne was not decisive in any way. It wasn't even about Ireland - yet it became one of the most iconic events in Irish history.
1688 - The Glorious Revolution
To explain the Battle of the Boyne one has to start at the root cause of it. King James II of England, a Stuart, aroused the suspicions of the Westminster parliament by his reactionary politics and his definite leanings towards the Catholic church. Succeeding his brother Charles II as king, James was already 51 years old and not expected to last. Or build a dynasty - he was childless. And next in line for the throne was Mary, Charles' niece, married to William - an obscure European nobleman currently Stadtholder of the (staunchly Protestant) Netherlands.
While his religious beliefs might have been tolerable for a while, James' claim to being the absolute ruler got the Houses of Parliament's collective feathers immediately into a ruffle. Less than 40 years ago a king's head was chopped off for similar aspirations. Four months after James II accession the first rebellion under the Duke of Monmouth (his nephew, albeit illegitimate) failed. The "Bloody Assizes" followed, ringing home the reality of absolute kingship.
The final straw arrived on June 10th, 1688, in the form of the Prince of Wales - as if by magic James had suddenly succeeded in creating a male heir! Catholic succession was ensured.
William put all his eggs into one basket, sailed for England and landed at Brixham on November 5th, 1688. Ensuring the support of English dissidents, William marched upon London, manage to throw James out of England. The "Glorious Revolution" was a success and on February 13th William and Mary were crowned joint sovereigns - after signing the Bill of Rights and effectively making absolute monarchy impossible.
Jacobites Versus Williamites
The Glorious Revolution ripped Britain politically apart - supporters of "the Old King" vowing to resist the political change by force. They became collectively known as the Jacobites, James being the English version of the Biblical name Jacob. Not surprisingly supporters of King William became known as Willamites.
To view this conflict as a religious issue is a futile exercise - though James' Catholicism caused suspicion and ultimately led to his downfall. Political issues were far more important. And the Protestant William actually had the support of Pope Innocent XI. And William's European allies were mainly drawn from the League of Augsburg - an anti-French cabal of nobility, but including Catholic states as well.
Battleground Ireland
Ireland became a battleground almost by accident - having left England, James II had de facto handed William the crown on a silver plate. His only hope of restoration was linked to a return to his realm. And only one part was considered secure and sympathetic enough - Catholic Ireland, effectively ruled by the Jacobite Tyrconnel.
Tyrconnel was determined to hold on to power in Ireland and played a diplomatic cat-and-mouse-game involving William, James and Louis XIV of France.
With French blessings and military support James II landed at Kinsale on March 12th, 1689, bent on re-conquering Ireland, than Scotland, then England. Several Jacobite successes followed and the Siege of Derry began on April 16th, the Williamites were seemingly losing on a big scale. And James even managed to establish his own parliament in Dublin.
But the military campaign of the Duke of Schomberg, at that time a Brandenburg general "on loan" to William, almost reversed the situation. And on June 14th, 1690, William III entered Ireland at the head of 15,000 troops (mostly Dutch and Danish) - using the port of Carrickfergus and heading south for Dublin via Newry and Drogheda.
James II decided to thwart this plan by defending Dublin on the banks of the River Boyne. Occupying Drogheda and the Oldbridge Estate to the west looked like a good idea at the time.
