How Dutch Orange symbolism entered Northern Irish politics

Why does orange appear in Northern Irish Protestant politics, and is it connected to the Dutch House of Orange?

Yes. It traces to William of Orange, though modern Orange politics is much more complicated than that origin alone.

The political use of orange traces back to William of Orange and the Dutch House of Orange. The Orange men drew their name and symbolism from that dynastic and Protestant connection. Its modern meaning has become much more complicated than those seventeenth-century roots. The answer is a genealogy of the symbol rather than a claim that current Northern Irish politics can be reduced to Dutch history.