Lag B'Omer, the 33rd day counting from Pesach (Yitsiat Mitzrayim, Leaving Egypt) to Shavuot (Matan Torah, Receiving the Torah) is coming up May 22. The Rabbis tell us it is the day the plague among R. Akiva's students lifted, leaving 24,000 dead for lack of midot. This doesn't explain the bonfires or the bows and arrows. Historians tell us the "plague" was a couple of Roman legions. Lag B'Omer commemorates the Bar Kochva rebellion, 132-135 ce, which established the last independent Jewish state in Eretz Israel for 1,813 years. The bonfires were for the dead. The Romans were real good at making inconvenient people dead. It was the third Jewish war against Roman suzerainty (67-70 ce, Masada, 115-117 ce, Kitos). Nobody rebelled against Romans like us.