Thoureau wanted to poit to the fact that following traditions limits us and deprives us from developing our imgination. Thoreau, like other romantic authors, does not agree with tradition. He thinks it prevents people from finding true greatness and blocks their path to spirituality. "Castles in the air" are simply illusions by which people persuade themselves in something that is not true, in Thoureau's opinion.
The event that set off World War I was the assassination of Archduke Franz Ferdinand of the Austro-Hungarian Empire and his wife Sophie by Gavrilo Princip, a Serbian nationalist, on June 28, 1914 in Sarajevo.
Foreign occupation gave the nationalists in the country a common cause to unite.
Explanation:
Foreign occupation is a phenomenon that has resulted in many nationalist movements across the world for a long time.
This is because the foreign rule in itself sows the common cause against which the nation can unite itself and then fight back or throw away with diplomacy their own rulers.
This common cause binds the thread of self determination and rule of the nation under one rule is what is requited for nationalism to rise and it happens here rather strongly.
The people of the nation set aside differences against a common enemy of the state.