Interesting Fact of the Day: Cannon shots in classical music, and their historical significance

What famous classical piece of music has 16 cannon shots written into the original score and includes portions of at least four other pieces of music?

And what connection does this classical piece by Tchaikovsky have with Napoleon Bonaparte?

As most everyone knows, Napoleon was a French dictator and general who made France a world superpower.  His power was finally broken, in the providence of God, by the British at Waterloo in 1815.  But the allied victory at Waterloo would not have been possible if it had not been for his disastrous campaign into Russia.  This campaign marked the beginning of the end for French dominion.

The Russians were comparatively poorly equipped and trained, no match for the French from a military point of view.  They were forced to resort to "scorched earth" tactics, retreating before the French army and destroying everything before them.  The French were thus forced to rely on an inadequate supply line for provisions in their advance to Moscow.  When they arrived in Moscow, they found the city in flames and learned that Tsar Alexander would rather sacrifice his capital than capitulate with them.  To make matters worse, the brutal Russian winter was coming.  Napoleon had no choice but to turn his dispirited Grand Armee around and leave.

The retreat from Moscow became one of the most discouraging pages in French military history.  Thousands of soldiers succumbed to the cold and starvation and the ones who survived were too dispirited and disorganized to win the War of the Sixth Coalition.  Napoleon was banished to the island of Elba, giving Europe a brief respite from his empire-building wars.

Now, to answer the first two questions:
The 1812 Overture has 16 cannon shots written into the score.

5 shots signify the French - Russian battle of Borodino; 11 more shots punctuate God Save the Tsar in the finale of the overture. It includes fragments of Lord, save thy people, La Marseillaise, U Vorot, Vorot, and God Save the Tsar. 

The 1812 Overture was written by Pyotr Illyich Tchaikovsky to commemorate Napoleon's invasion of Russia, Tchaikovsky's home country.  This Wikipedia article explains the overture more fully, and it is amazing how this piece comes to life (at least, for me) after reading the article.

While the Russian Orthodox faith was mostly apostate and the Czarian rule of Russia was little, if at all, better than Napoleon's rule of France, God used the Russian campaign to break the power of the deist French dictator, Napoleon Bonaparte.

So, if you are interested in listening to the 1812 Overture, check out this YouTube video (music only).  It is an amazing musical commemoration of Russian and world history.