In November 1925, after Frunze's death, Yakir was appointed commander of the most powerful territorial formations of the Red Army, the newly reorganized Ukrainian Military District (see: Kiev Military District). Yakir, in close coordination with Tukhachevsky and other reformers, made his district into a laboratory of wide-ranging experiments in strategy, tactical and operational techniques, army formations and equipment. In training his troops, Yakir encouraged his officers' initiative and ability to make their own judgments. In 1928 and 1929, Yakir studied at the Higher Military Academy in Berlin. This was possible because of the intensive military cooperation between the Soviet Union and Germany. Yakir's innovative approaches to the military art impressed his German colleagues. German Field Marshal of World War I fame, Paul von Hindenburg, praised him as one of the most-talented military commanders of the post-World War I era. Upon repeated requests from German officers, Yakir gave special lectures on the Russian Civil War.