Eleven firefighters – two Forest Service personnel and nine from Viejas Honor Camp – lost their lives fighting this human-caused fire west of Julian, California on November 25, 1956. Soon after this fire, the 10 Standard Firefighting Orders were developed.

This was one of the first fires where sodium calcium borate was used as a fire retardant dropped from an air tanker. It was quickly discovered that this chemical sterilized the soil, and by 1957 it was no longer used. However, the term “borate bomber” lingered on for decades.

For more info
http://www.wildfirelessons.net/documents/Inaja_Forest_Fire_1956.pdf
http://legacy.signonsandiego.com/uniontrib/20061125/news_1n25inaja.html