Proxying request without modifying source URL

I have two servers, one that runs in the US, and one that runs in the EU.

My US server is at, and my EU one is at

I have a basic CF worker that can proxy the request from the US address to the EU one, but it is of course, causing a change in the URL in the browser.

I would like to actually do the request to the EU server, and send the response back without the URL in the browser changing. So it looks like you went to the US domain but in fact, the worker went to the EU domain on your behalf and brought back the response.

I see that I can just do something like

addEventListener(“fetch”, event => {

and this returns that static content to my US domain request.

I’m hoping to be able to do this against a Web app server (and the proxied request is hitting my EU app server).