What's a Deathmarch?

Brad wrote to us that he and his companion had been on a deathmarch. We wrote back asking "What is that?" We are sure you wanted to know. According to Brad a deathmarch is "when you basically do nothing except tracting for every minute of the day, and usually meet with no success." He did this with his first "son" along a 16 mile long highway between these two towns. "We did the whole thing, and didn't find a single investigator!"