The 6-inch guns in the foreground are US Army M1900 guns on the M1900 pedestal mount with shields removed; they are possibly about to be mounted on field carriages for service in France. Alternatively, the photo may date from circa 1905, when this type of weapon was being manufactured.
<div class="fn value">
Unknown author<span style="display: none;">Unknown author</span> or not provided</div>
circa 1918 <div style="display: none;">date QS:P571,+1918-00-00T00:00:00Z/9,P1480,Q5727902</div>
<a href="https://en.wikipedia.org/wiki/U.S._National_Archives_and_Records_Administration" class="extiw" title="en:U.S. National Archives and Records Administration">U.S. National Archives and Records Administration</a>