Just like that. On Sunday, April 13th, 3:21PM, Dice_Thrown provided the correct answer . . .

It was JapaneseLoneWolf, who was promoted from Leader to Clan Officer. He did not guess the date and time, which was March 31st, 7:48PM.

When I was given the new promotion, I wanted to celebrate with the entire clan, so I thought of the contest. Since I joined the clan, I have made new friends who I enjoy very much playing with. We have lots of laugh and the game is fun when you run with a group of like minded people. Warframe is more than a shoot-em-up, it takes teamwork and a bit of strategy to win. The online friends I made I would have never met otherwise. Henceforth, the contest. It is an honor to be Clan Officer, and I wanted to give back to everyone who assisted me in having lots of fun, as well as building the clan to where it is today.

There will be more and various clan contests like this in the future, so stay tuned as they appear.