I cannot remember where I came across that information. It was in a biography, I believe, but I've read several on Moody (I only own two and have no idea where they are). So I may have my evangelists mixed up.
What I remember (again, if my memory serves me correctly....batting 50/50 right now) early on Moody combined social work with evangelism to reach the lost. He was president of the Chicago YMCA for four years and used community outreach programs within the YMCA as evangelistic tools. If I recall, wasn't that how he ended up partnering with Ira Sankey? He used YMCA programs not only to witness to those he contacted but also to develop programs to distribute tracts and hold prayer meetings.
Moody concentrated heavily on social programs to assist the flood of immigrants in Chicago, even holding English classes to teach those who did not know the language. I may have the wrong person, but I believe that these were the works of Moody because, if I recall, after the Chicago fire he ended the social work aspect of his ministry and focused strictly on evangelism.
I hate referring to things without being able to provide a reference. I will try to find the book. I am fairly confident that it was Moody who combined social work and evangelism early on, mostly because that evangelist changed this after the Chicago fire,and Moody is the only one who comes to my mind when I think of great evangelists and the Chicago fire.