On that day, a squadron of Mounted Jager Regiment set foot onto the Egyptian Bridge in Saint Petersburg. The passers-by admired the gallant cavalrymen, while horses stamped. This ordinary redeployment of the squadron made its way into all textbooks, yet not the ones of warfare or history. This march was mentioned in the physics textbook in chapter Resonance. The beautiful chain bridge, decorated with hieroglyphics and Egyptian ornaments started vibrating, the frequencies coincided, and the cavalrymen found themselves in icy water of Fontanka River, and this time made their way to the records of history – the photographic report shows the collapsed bridge and episodes of saving the soldiers.