whatever guderian's initial level of enthusiasm for manstein's operational plan, he became supportive of the idea from november onwards, whereas much of the german supreme command did not initially share either man's optimism for the "sickle cut". manstein. previously chief-of-staff for army group south, was replaced by georg von sodenstern and himself shipped off by franz halder, chief of oberkommando des heeres between 1938 and 1942, to command xxxviii army corps, a newly formed corps that consisted of third wave recruits. according to guderian, it took until wargames in february 1940 for the idea to be seriously considered once again.the commanders of army group a, which xix army corps was a part of, met on 15 march 1940 to discuss finalized operational goals. by now, manstein's idea had been approved, and it thus became guderian's task to cross the border to luxembourg, advance towards southern belgium and then sedan, to cross the meuse at sedan and to erect a bridgehead of the river's left bank. guderian estimated that he would reach the river on the fourth day of the operation and attack across the river on the fifth. xix army corps would be one of two major armored corps, the other being xiv army corps under gustav anton von wietersheim, as had been envisioned by manstein.