A little more to it than that. My father's division, the 27, was put with the 30th (Pennsylvania NG, I think), to form the US 2d Corps. Pershing was an old fox, he got another three star position out of that. Then, to silence those who wanted his troops, he gave the 2d Corps to the British. They fought under the British 4th Army, General Gough commanding.
They were completely re-equipped with Rritish uniforms, kit, weapons and rations. My father didn't think much of the British rations, and he expresssed himself about British rifles in a diary entry: "Went to the range today. Shot a pretty good score considering I was shooting a Lee-Enfield". It worked out pretty well for him, despite having to carry a Mk III* Lee Enfield into battle; he was the corporal of a machine gun squad. If he had stayed with the American army, he would have had the abminable French Chauchat, or perhaps the even more abominable version in 30-06. Instead his squad had the Lewis in .303.