Given the question: Question: "What was a primitive form of alarm using a repurposed weapon?"  Context: "During his time as an American envoy to France, Benjamin Franklin, publisher of the old English proverb, "Early to bed, and early to rise, makes a man healthy, wealthy and wise", anonymously published a letter suggesting that Parisians economize on candles by rising earlier to use morning sunlight. This 1784 satire proposed taxing shutters, rationing candles, and waking the public by ringing church bells and firing cannons at sunrise. Despite common misconception, Franklin did not actually propose DST; 18th-century Europe did not even keep precise schedules. However, this soon changed as rail and communication networks came to require a standardization of time unknown in Franklin's day."  Answer:
The answer is:
firing cannons