This thread hit a spot with me. About three years ago, realising late in life how little I knew about my maternal grandfather, killed in the withdrawal from Le Cateau some two weeks into WWI, I started to write a Memoir, based on my Logbooks, something that one day might mean something to my daughters and granddaughters. I reckoned that it would therefore need a good deal of context to have meaning and significance in years ahead, and that led me down a number of paths - for example, scanning a simple Airplot diagram to help explain the basics of navigation as we learned it in the 60s; explaining what the Transport Command Cat Scheme was; and so on. (Just mentioning these suggests that they are already 'history.')
I also felt I had to mention background political developments - things like Rhodesian UDI and the events attendant upon our withdrawal from Aden, which happened to have a significance in my personal narrative. And what I found was that my memory of dates and chronology was not as sure as I had spent many years thinking - broad detail was fine, but checking things via Google showed that not everything could have happened quite as I had allowed myself to imagine. Just a thought to pass on to others who feel the need to put finger to keyboard.
I left the result of it all on my hard disk and, on looking back at it recently, I now realise that there are bits and pieces that need to be corrected. So, if there is a message anywhere in this, it might be that the sooner you get a first draft written down, the better. Your memory does not improve with the passage of the years!