What is the theme for Easter 1916 by William Butler Yeats?

The final line of the stanza: "A terrible beauty is born,"(16) describes the people of Ireland as they come together and work towards the goal of Irish independence from England. The birth of these united people is terrible because the fight for independence will inevitably cause bloodshed and death. It is also beautiful because the people are finally uniting and standing up for their beloved country. This is the first time this line is introduced to the poem. It is repeated throughout the poem and creates the poem's main theme.