The main cause was the conquest by the Ottoman Turks in 1453.
means to cause a downfall
because it is a myster
He died prematurely.
Downfall in what? A bigger or more organised gang beat them. Which is not too difficult. Weeds do it.
His death. He was emperor until he died.
because they want something change to their government
The horses failed.
Yes, the compound noun 'downfall' is a common noun, a general word for a loss of power, prosperity, or status; a general word for the cause of such a loss; a general word for any downfall of any kind.
they died cause they shot each other
Nationalism, corruption, technological and economical downfall
The downside of Industrialization is that its main downfall is that it causes global warming. melting the polar ice caps, causing animals who couldn't live in Canada able to live in Canada cause of warming temperatures.