Complex sentence: Furthermore, Hitler did not like Halder's objecting to Hitler's decision to send General Manstein's 11th Army to assist in the attack against Leningrad, nor to Halder's criticism that the German attack into the Caucasus was ill advised.
Split into simpler sentences: Furthermore, Hitler did not like Halder's objections to sending General Manstein's 11th Army to assist in the attack against Leningrad. Halder also had thought that the German attack into the Caucasus was ill advised.