Under the Penal Laws, the Irish Catholics could not hold commission in the army, enter a profession, or own a horse worth more than five pounds. Catholics could not possess weaponry and arms, could not study law or medicine, and could not speak or read Gaelic or play Irish music. The law around land ownership and how it was inherited cause 90% of the population to own only 10% of the land. It caused widespread poverty, hunger, homelessness and immigration. People from other countries traveling in Ireland and reporting on their observations could not believe the deplorable inhumane conditions the British were inflicting. Through it all, the resilient Irish people went from oppression to nationalism!
Irish Mythology - Mythical Cycle - Book of Invasions