As difficult as it is to imagine, likely the reason why the First World War is not seen as the most disastrous upheaval in European Jewish history is because of the Second World War far eclipsed it. (Although admittedly I am far from well read in this area, and if I made an outrageous claim here, I'll be happy to be corrected.)
The following report was received by the American Joint Distribution Committee in 1916, by Drs. Paul Nathan and Bernard Kahn who took a trip "through Courland and Lithuania" on behalf of the Jüdisches Hilfskomite für Polen.
You can read the full report here. Since the rest of it discusses Courland, Libau, Schaulen, Kovno, Vilna, Lida, Grodno and Bialystok in addition to Slabodka, I probably should think about whether I, too, favor the Yeshiva -- with this post.
In any case, the report concludes by tallying the amount of aid spent in all of Poland and Lithuanian in the single month of January, and recommends that at least that amount by spent in the months following. In my very inexact calculating, I found that the amount was approximately $770,000 in today's dollar. In other words, probably enough to buy a lot of bread and medicine for tens of thousands of suffering people, but obviously much more would have been needed. Incidentally, another report also points out that American Jews had been sending about 5-600,000 Marks monthly (which would seem to come out to more than twice the sum mentioned above) but at that point the English had begun to not let any mail through, with the result that this resource had dried up.