Certain to occur is the best choice. Key words in the passage such as "anxiously" should lead readers to understand that the war was to begin in the near future. Background knowledge such as knowing that the Civil War did ultimately came to fruition also assists readers to make meaning.
my child is yet a stranger in the world; she hath not seen the change of fourteen years, let two more summers wither in their pride, ere we may think her ripe to be a bride.
