 Lahm sailed from New York City on August 23 aboard the RMS "Baltic" and arrived in England on September 15, 1917, where he began keeping a war diary.Lahm's assignment in England began with nine days of inspections of factories, depots, and training fields.On September 24 he flew the English Channel as an observer on a Bristol Fighter, landing at Saint-Omer and continuing on to Montrouge, where the 2nd Wing, 2nd Air Brigade of the British Second Army was situated.