The phrase "downfall by" is correct and can be used in written English.
It is typically used to show that something or someone caused a downfall or demise. Example: The company's downfall by poor financial investments led to their bankruptcy.
"Downfall," by Peter J. Boyer, November 20 , 2006
His excesses brought his downfall by military coup Colombia's first in the 20th century.
In 2007, Musharraf triggered his own downfall by sacking the sitting chief justice, Iftikhar Chaudhry.
9. Adolf Hitler: My Part in His Downfall by Spike Milligan Is it a novel?
In these Icarus-like stories, protagonists are driven to their downfall by their own self-belief.
That does not mean that they would respond to his downfall by marching on their own governments.
Every time a posho or politician referenced the video, Gangnam sprang back to life – Lazarus-like – from the cyber-graveyard where all memes go to die (that's Rebecca Black over by the mausoleum; Downfall's by the church wall, underneath Kim Jong-ilookingng at... things).
Pretty sure that we (humans) will bring about our own downfall, either by blowing each other up, or by inventing a robot that says, "You guys are idiots, so I'm going to kill you".
[cartoon id= a20475"] Comencini hopes that Berlusconi and Trump may end up having something else in common: a downfall catalyzed by women.
Maybe you didn't know he was head of Paramount Pictures overseeing megahits like "Chinatown," "Rosemary's Baby," "Love Story" and "The Godfather" or that he suffered a great downfall, accompanied by cocaine.
For 21st Century Fox, the initial harassment lawsuit that led to Mr. Ailes's downfall, filed by the former anchor Gretchen Carlson, seems like a break in the moldy wall of an old house.
