Have a look at this video which explains why you use fue rather than era. 

https://youtu.be/VKjPJao-UKw

Hola,

This was really worth watching. I think "Juan" has a gift for explaining a topic and was really entertaining in the process. There wasn't anything particularly new compared to what we have been taught on this course, but it was explained beautifully and humorously in very understandable / not highly accented Spanish with some excellent examples. Fun learning. 

He's great. If you have Spotify and if you haven't already, check out his podcast, español con Juan!