Complex sentence: On 26 September 1941, the 52nd Army headquarters was used to form the 4th Army (II Formation) and the 52nd Army headquarters itself was reestablished on 28 September 1941.
Split into simpler sentences: On 26 September 1941, the 52nd Army headquarters was used to form the 4th Army (II Formation). The 52nd Army headquarters was reestablished on 28 September 1941.