The German S-mine (Schrapnellmine, Springmine or Splittermine in German), also known as the "Bouncing Betty" on the Western Front and "frog-mine" on the Eastern Front, is the best-known version of a class of mines known as bounding mines. When triggered, these mines are launched into the air and then detonated at about from the ground. The explosion projects a lethal spray of shrapnel in all directions. The S-mine was an anti-personnel mine developed by Germany in the 1930s and used extensively by German forces during World War II. It was designed to be used in open areas against unshielded infantry. Two versions were produced, designated by the year of their first production: the SMi-35 and SMi-44. There are only minor differences between the two models. The S-mine entered production in 1935 and served as a key part of the defensive strategy of the Third Reich. Until production ceased in 1945, Germany produced over 1.93 million S-mines. These mines inflicted heavy casualties and slowed, or even repelled, drives into German-held territory throughout the war. The design was lethal, successful, and often imitated. History French soldiers encountered the S-mine during minor probes into the German Saar region on September 7–11, 1939, during the Saar Offensive. The S-mine contributed to the withdrawal of these French incursions. The mine's performance in the Saar region affirmed its effectiveness in the eyes of the German leadership and prompted the United States and other countries to copy its design. After their experience, the French nicknamed the mine "the silent soldier". The Third Reich used the S-mine heavily during the defense of its occupied territories and the German homeland during the Allied invasions of Europe and North Africa. The mines were produced in large numbers and planted liberally by defending German units. For example, the German Tenth Army deployed over 23,000 of them as part of their defense preparation during the Allied invasion of Italy. S-mines were deployed on the beaches of Normandy in preparation for the anticipated invasion as part of a general program of heavy mining and fortification. On the Îles-St.-Marcouf, just off Utah Beach, where the Allied planners feared the Germans had established heavy gun batteries, Rommel had ordered S-mines to be "sown like grass seed." To build the Atlantic Wall, Germans deployed millions of mines of various types, anti-personnel mines (such as the S-mine), dug hundreds of kilometers of trenches, laid barbed wire, and