The Battle of the Boyne has arrived – a moment greeted with incredible significance by some people in the UK, and confusion by others. The event is a public holiday in Northern Ireland and marks one of the most controversial and important parts of British history. And it is marked by a message in people's iPhone calendar, which has the tendency to confuse some people who see it. For people in Northern Ireland, that fact is obvious: they have the day off, and the controversial celebrations are hard to miss. But for the rest of the UK, the only reminder might be a cryptic note inside their iPhone calendar. What is the Battle of the Boyne? Historically, the name refers to the 1690 event where the Catholic King James II's troops were defeated by the Protestant William III. Nowadays, it is an annual bank holiday that commemorates the same battle. The original battle was of incredible significance not only to the history of Ireland but across Europe. It brought about the conclusion of a fight for the throne in England and is a key part of the ascendency of Protestants in Ireland. Now each year, the holiday takes place on 12 July, an event known as "The Twelfth". It is commemorated by the Protestant community, and it is often marked by confrontations in Northern Ireland. Why is it in my iPhone? The iPhone keeps a full log off all the public or bank holidays in the UK, or wherever else your phone happens to be. That can be very useful because Except sometimes it will throw up strange examples, such as the Battle of the Boyne. The reminder might be very useful for people in Northern Ireland – but for the rest of the UK, where people don't have the day off, it probably mostly useless. That's because the calendar counts every holiday in the UK, even if it does not apply to you. The different parts of the UK have different holidays, and each of them show up in the calendar. It doesn't just include the Battle of the Boyne. The calendar will also show all of the Scottish bank holidays – such as the extra day off at New Year, and the different summer bank holiday – as well as St Patrick's Day, for which people in Northern Ireland are given a holiday too. How do I get rid of it? In short, you can't. The calendar isn't really yours, but is created by Apple, meaning that you can't change it either. You can get rid of the calendar entirely – that is done by clicking the "Calendars" button at the bottom of the screen and deleting or hiding the UK bank holidays one – but that will mean you'll also lose the entire calendar along with it. You could of course recreate the functionality by adding the dates yourself, but that is difficult since some bank holidays tend to move around depending on how days line up. You can add and subscribe to custom calendars on your iPhone, using links that can be found on the internet. The trouble is that all of the examples for bank holidays – such as the one provided by the UK government – also include the Battle of the Boyne. You can make the event slightly less irritating, by turning off any alarms that are associated with it. That is done by clicking on the event on your iPhone and pressing the "alert" button, where you can choose "none". But either the event stays, or you lose all the other bank holidays. Read More New iPhone software stops hackers getting into handsets through USB Why the Battle of the Boyne has made its way into your iPhone Twitter gets strange endorsement from Taliban over rival Threads Instagram Threads hits 100 million users