Defection was a serious problem in the Red Army, particularly in the first year 
of the war, and the Soviets countered it with their own form of military terrorism. 
In May 1942 the NKVD* organization was established under 
L.P. Beria the chief of internal security, to deal specifically with military 
deserters. NKVD was given enormous power to deal with those suspected 
of disloyalty and their families, including that of execution without trial. 
A new guidance on penal battalions was also published. By May 1942 each 
Russian front commander had ten to fifteen penal battalions at his disposal. 
The battalions were headed by staffs or ordinary soldiers and officers. 
Discipline was enforced by a guard company. Staff and guards were highly 
paid and got special pension benefits for this unpleasant and sometimes 
dangerous work.  The penal units (not only battalions)were used widely
and were not allowed weapons until they entered the line. 
All soldiers in penal units knew they have the only two chances:
to win or to be killed. (The famous 16th Army of Rokossovsky was
completely penal).
They often attacked through minefields as "tramplers", whose bodies by the
score marked the passage of the Red Army through a field. In the assault on the
"Cauldron" at Stalingrad sixteen penal battalions were concentrated in the 21st 
Soviet Army area and twenty-three in the 65th Army area on the Don Front. 
Official Soviet army casualties during the war were listed as 20 million 
but were actually much higher, including the penal battalions, whose 
statistics were not kept. Gorbachev gave another figure, 27 million, in May 
1991. In most Soviet attacks, several penal battalions were completely wiped 
out. 

* About NKVD : Narodniy Komissariat Vnutrennikh Del : The Ministry of Internal Affairs

January 1, 1941  -  3rd Section of GUGB (P.V.Fedotov)
January 1, 1942  -  2nd Section of NKVD (P.V.Fedotov)
January 1, 1943  -  2nd Section of NKVD (P.V.Fedotov)
January 1, 1944  -  Section of Counterespionage "SMERSh" (S.P.Uhimovich)
January 1, 1945  -  Section of Counterespionage "SMERSh" (V.I.Smirnov)