How did Johnny know that British troops were getting edgy and nervous?

I think this is actually in Chapter 9. Mounting tensions make it harder for Johnny to do his job as a delivery boy. He notices nerves are on edge. British officers often pull him aside and question him. One day, they threaten to flog him simply for walking his horse down the street and being employed by the Boston Observer.

Mounting tensions make it harder for Johnny to do his job as a delivery boy. He notices nerves are on edge. British officers often pull him aside and question him. One day, they threaten to flog him simply for walking his horse down the street and being employed by the Boston Observer.