Would a different Preparedness Movement have changed the US's viewpoint, maybe not the general populace but perhaps leaders who were in the know, on war?
After the successful reforms under SecWar Stimson the administration of SecWar Garrison saw no major movement forward in the reform and preparedness of the US Army. Garrison backed the 'Continental Army' plan to expand the Regular Army and create a reserve but marginalised the National Guard, a plan which didn't please anyone so it died a death.
WI Garrison, for whatever reason and perhaps by sheer fluke, plumps for the plan which IOTL was successful and became the 1916 Defense Act; basically doubling the size of the Regular Army to 200,000 and expanding the NG to 440,000? Sorting out this political issue nice and early could transform both the preparedness of the Army, the 1916 DA saw the immediate raising for 3 new artillery regiments including 1 of 6" howitzers (the RA only had 6 artillery regiments in early 1916, only 1 had 4.7" guns and howitzers) and the political decisions concerning the trouble in Mexico and in Europe.