What does "From Castles to Cannons" Title really mean?

 If you have studied warfare in history you know that castles were only useful and knights in armor were only useful before cannons and muskets. 9-11 which used passenger planes as missiles filled with people into the world Trade Center also took away our feelings of security because mainland U.S. had not been usefully attacked since the British in the War of 1812 when they burned Washington DC and the Capitol then. So, this was the first major attack upon the U.S. mainland since the 1812 war unless you consider Pearl Harbor which happened in Honolulu. However, the mainland was not directly attacked that time.

How do you think the owners of castles and knights with armor felt when cannons and powerful guns that could pierce knights in armor came upon the scene? A Cannon can be built strong enough to break down the walls of almost any castle made of Rocks and mortar. Or at least the gate of the castle can be breached by a cannon almost no matter how you build the castle itself.

So, using passenger planes as missiles into the two World Trade center buildings and the Pentagon and luckily the passengers brought down the Shanksville plane before it destroyed the Capitol Building like it was in the war of 1812.

Begin quote:

On August 24, 1814, as the War of 1812 raged on, invading British troops marched into Washington and set fire to the U.S. Capitol, the President's Mansion, and other local landmarks.

Burning of Washington, 1814 - Senate.gov