In 1992 I wrote a political thriller called Kiss of the Assassin. One of its subplot centres around the Soviet Union's involvement in the Vietnam War and later the union's eventual collapse.
After months of research, years of editing, six workshops, revisions, and help with my query letter, I submitted to every agent/publisher in my genre. The response back was the same, “Sorry, no one's interested in Vietnam.”
This year, because of a renewed interested in the War, I pulled Kiss from the shelf and subbed a few chapters to my online writer's group.
Footnote: In the 90s if you told me what company you served with in Vietnam, I could estimate where you were and what major incidents you may have encountered during your tour.
Twenty years has passed since I began Kiss, fifteen years since I set it aside. Why couldn’t I, considering the initial response of my writer’s group, do a quick proofread and start querying?
One of my beta readers read an article recently first published in 2006 by a Russian defector on the killing methods of the KGB. While my research on the Soviet Union was thorough in the 90s, that article alone proved I no longer had command of my subject matter.
Information revealed in the article stated that the KGB assassins used undetectable radioactive compounds that mimicked cancer and killed within days. My assassin in Kiss of the Assassin uses an empty syringe. This is not a huge blunder by itself, but coupled with the two other inconsistencies he found would have shattered my credibility as a writer.
After two published novels, a collaboration, a silver medal for my 2nd novel, I know I can write. But had I sent out this manuscript without fixing the inaccuracies, I would have either ruined my chances of finding a publisher or proven I was an unreliable storyteller.
Before assuming your edited, critiqued, revised manuscript (no matter how young) is ready to submit, always, always, always seek the help of beta readers you trust; or better, if you can afford it, hire a professional fiction editor.
Don't allow even the smallest of novice mistakes to ruin your chances. Never submit your manuscript too soon.