The paragraph is an excerpt from "The Story of Lucy Gault" by the Irish short story writer William Trevor.
The past was the enemy in Ireland
1.Does it mean: in past somethings had happened and because of that these trouble was happening in Ireland?
OR.
2.in the past there was an enemy in Ireland?
The first sentence accurately defines "the past" as it refers to Ireland's history
The very beginning of the story describes an incident that happened one night in the summer of 1921 during Ireland’s final struggle for independence.
Three arsonists — shadows in the night -- arrive at Lahardane, the home of Captain Everard Gault, his wife, Heloise, and daughter, Lucy.
Everard's single shot accidentally injures one of the intruders
(named Horahan). His apologies and offers of restitution to the boy and his family are ineffective.
Everard, a former British army officer; Heloise, an English wife and mother; Lahardane, an ancestral Irish property since the eighteenth century. It is too dangerous for them to stay. They too must desert Ireland like so many families before them.
Ref. amazon.com
OP's passage reflects the emotional state of eight-year-old Lucy Grant, who is unwilling to leave Ireland.