Complex sentence: In February 1901, he became a Major General in the regular army and from July of that year until October 1902 served as the military governor of the Department of the Philippines, during the beginning of the 2nd phase of the Philippine-American War.
Split into simpler sentences: In February 1901, he became a Major General in the regular army. From July of that year until October 1902, served as the military governor of the Philippines, during the beginning of the 2nd phase of the Philippine-American War.