Loegaire was a son of Niall of the Nine Hostages and brother of Eogan. Loegaire became High King of Ireland in 428 A. D. and ruled from Tara. In 433 Loegaire decreed that no one should light the paschal fire on Easter eve until Loegaire himself had kindled the fire on Tara's hill, signaling the return of spring and beginning the pagan spring festival. In his attempt to convert pagan Ireland to the light of christianity, St. Patrick defied the King. Patrick lit a bonfire upon Slane Hill on the eve of the Christian feast of Easter which coincides with the pagan feast of Beltane and the spring equinox.
The King rode off in a war chariot with his retinue to arrest the mystery rebel. As the kings horses thundered up Slane Hill, Patrick calmed his few disciples and immediately set to eloquence. Somehow - some say through an earthquake, others say by holding up a shamrock - he convinced Loegaire of his earnest intent and belief in the power of the Holy Trinity. It was a power that Patrick thought would be useful to the King who could only wish that his own soldiers could wield the kind of bravery through deep conviction that Patrick displayed.
The King took Patrick and his disciples prisoner and they were marched to Tara's Hill, chanting prayers. By morning light, Patrick and his men were spared and allowed to preach Christianity to the pagan army.
Loegaire was so impressed by Patrick's devotion that, despite his defiance, he let him continue his missionary work
throughout Ireland. Because of this, one of the many legends surrounding Patrick credits Loegaire with the establishment of
Christianity in Ireland. Loegaire tolerated the new faith, although he did not wholeheartedly accept it himself. He died
in battle, and by his own orders was buried (at Tara) standing upright with his
face towards his foes.