Shaun Edwards says he almost quit rugby union for the Australian Rugby League after being overlooked as part of Warren Gatland's British and Irish Lions backroom staff.
The Englishman joined Wales as assistant coach to Gatland in January 2008 and masterminded a defence which conceded just two tries in 400 minutes in winning that season's Six Nations Championship and Grand Slam.
Wales were similarly miserly in the 2012 championship, conceding just three tries, and none at all, in the final three Tests against England, Italy and France in completing another clean sweep.
Edwards had earlied helped guide London Wasps, alongside Gatland, to two Heineken Cups, four English Premiership crowns, one European Challenge Cup and an Anglo-Welsh Powergen Cup triumph.
But, after Gatland chose England's Andy Farrell as defence coach for the Lions' tour of Australia this summer, Edwards was forced to reassess his position with Wales.
The former Wigan Warrior rugby league star insisted Saturday's Six Nations triumph, thanks to the stunning 30-3 win over Slam-chasers England, justified his decision to continue.
"This one (title) is special for a personal reason, if only because it wraps up a period which started in a dark place," Edwards wrote in the Guardian.
"I've had plenty of highs in my professional life - 42 medals as a player, 11 trophies in 12 years as a coach - but the time that tested me most was the three days after discovering that I wasn't going to be part of the Lions coaching squad this summer.
"Whereas 2009 with the Lions in South Africa was one of the big highs, hearing that I was not going to be part of the set-up in Australia made me want to chuck the whole lot in.
"There were ideas of turning my back on union, going back to league, possibly even leaving the country to re-learn my trade as an assistant coach with the ARL.
"It took me 72 hours to banish those ideas and, on Saturday, among the Welsh players and fellow coaching staff, I understood why I did. They've been great to me, treating me as one of their own and it's a lucky man who can be part of such a set-up."