I just want to amend something I wrote and intended to qualify but I was timed out of editing my post after spending too long doing research on the matter.
Russell's booklet "The object and Manner of Christ's Return" of 1877 said that the failed 1874 Adventist claim for the return of JC was not a failure, it happened... but invisibly. This was through reliance on the Emphatic Diaglott's rendering of the Greek word 'parousia' meaning 'presence' instead of the traditional 'coming'. This was the critical contribution which Russell thought he was bringing to mankind. Secondly it was the founding message for the reason for Watchtower magazine starting in 1879.
“When I use a word,” Humpty Dumpty said, in rather a scornful tone, “it means just what I choose it to mean—neither more nor less.”....................................Lewis Carrol
Prominent in the minds of the religious Christian majority in USA was the idea of Christ's visible return as in the scripture "Every eye will see him". Russell said yes, but not all at the same time! And then gave weasely reasons to support it.
I believe that his enormous popularity as a preacher in the first fourteen years of the nineteenth century was due to giving a positive spin on the end of the world and a verbal certainty and conviction to the fulfillment of Bible promises on the return of Christ.
When dealing with religious ideas, logic is irrelevant. Whether there was WWI or not, Russell failed as a Bible prophet as have all his forebears and successors including JWs, because religious belief is independent of facts and world events, it has no substance, it is just spin and hope.