Unfortunately for Sibert, when the United States entered World War I in April 1917, Brigadier General Sibert was one of the only senior infantry officers on active duty.<unk> Unfortunately for Sibert, when the United States entered World War I in April 1917, Brigadier General Sibert was one of the only senior infantry officers on active duty. ️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️ AEF commander, General John Joseph Pershing, a long serving infantry officer famous for his exploits at San Juan Hill
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