Discovery Channel's new two-part, four-hour special "The Presidents’ Gatekeepers" (premieres Wed., Sept. 11 and Thurs., Sept. 12 at 9 p.m. ET) takes a look at the power behind the presidency: The White House Chiefs of Staff.


Featuring commentary and never-before-heard stories from all 20 living White House Chiefs of Staff -- spanning nine administrations and more than 50 years -- it's a fascinating look at moments in history from a completely new, insider perspective.


We've got an exclusive sneak peek, above, at an historic moment in recent history: President Ronald Reagan's speech challenging then-Soviet statesman Mikhail Gorbachev to tear down the Berlin Wall to show support for the increased freedoms in the Communist Eastern Bloc.


Reagan's most quoted line from the speech is a powerful one -- "Mr. Gorbachev, tear down this wall" -- but can you believe it almost didn't make it into the final speech? Watch our sneak peek of "The Presidents' Gatekeepers," above, to hear the whole story.


Tell us: Are you surprised to hear this new side of the story? What other epic presidential moments almost didn't happen?


"The Presidents' Gatekeepers" two-night, four-hour event premieres Wed., Sept. 11 and Thurs., Sept. 12 at 9 p.m. ET on Discovery Channel.



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  • TV Critics Picks: 2013-2014 TV Season


    <strong>HuffPost TV gathered 19 TV critics to share their picks for the following topics: <a href="http://www.huffingtonpost.com/2013/08/26/best-new-tv-comedy-2013-critics-video_n_3813852.html" target="_blank">Best New Comedy</a>, <a href="http://www.huffingtonpost.com/2013/08/27/best-new-tv-drama-2013-critics-video_n_3820528.html" target="_blank">Best New Drama</a>, <a href="http://www.huffingtonpost.com/2013/08/28/favorite-tv-stars-2013-critics-video_n_3825994.html" target="_blank">Favorite New Stars</a>, <a href="http://www.huffingtonpost.com/2013/08/29/returning-tv-shows-2013-critics-video_n_3833912.html" target="_blank">Returning Shows We Love</a> and <a href="http://www.huffingtonpost.com/2013/08/30/worst-new-tv-show-2013-critics-video_n_3839731.html" target="_blank">Worst New Show</a> of the 2013-2014 TV season. <em>Watch the videos to see who picked what, then click through this gallery to find out when the shows premiere. </em></strong>




  • Worst New Show: "Super Fun Night"


    "Super Fun Night" premieres Wed., Oct. 2 at 9:30 p.m. ET on ABC.




  • Worst New Show: "Dads"


    "Dads" premieres Tues., Sept. 17 at 8 p.m. ET on Fox.




  • Worst New Show: "We Are Men"


    "We Are Men" premieres Mon., Sept. 30 at 8:30 p.m. ET on CBS.




  • Worst New Show: "Sean Saves the World"


    "Sean Saves the World" premieres Thurs., Oct. 3 at 9 p.m. ET on NBC.




  • Worst New Show: "Ironside"


    "Ironside" premieres Wed., Oct. 2 at 10 p.m. ET on NBC.




  • Worst New Show: "Welcome to the Family"


    "Welcome to the Family" premieres Thurs., Oct. 3 at 8:30 p.m. ET on NBC.




  • Worst New Show: "Reign"


    "Reign" premieres Thurs., Oct. 17 at 9 p.m. ET on The CW.




  • Worst New Show: "Back In the Game"


    "Back In the Game" premieres Wed., Sept. 25 at 8:30 p.m. ET on ABC.




  • Worst New Show: "Betrayal"


    "Betrayal" premieres Sun., Sept. 29 at 10 p.m. ET on ABC.




  • Favorite Returning Show: "Game of Thrones"


    "Game of Thrones" Season 4 premieres Spring 2014 on HBO.




  • Favorite Returning Show: "Scandal"


    "Scandal" Season 3 premieres Thurs., Oct. 3 at 10 p.m. ET on ABC.




  • Favorite Returning Show: "Parks and Recreation"


    "Parks and Recreation" one-hour Season 5 premiere airs Thurs., Sept. 26 at 8 p.m. ET on NBC.




  • Favorite Returning Show: "New Girl"


    "New Girl" Season 3 premieres Tues., Sept. 17 at 9 p.m. ET on Fox.




  • Favorite Returning Show: "The Walking Dead"


    "The Walking Dead" Season 4 premieres Sun., Oct. 13 at 9 p.m. ET on AMC.




  • Favorite Returning Show: "Homeland"


    "Homeland" Season 3 premieres Sun., Sept. 29 at 9 p.m. ET on Showtime.




  • Favorite Returning Show: "Boardwalk Empire"


    "Boardwalk Empire" Season 4 premieres Sun., Sept. 8 at 9 p.m. ET on HBO.




  • Favorite Returning Show: "The Mindy Project"


    "The Mindy Project" Season 2 premieres Tues., Sept. 17 at 9:30 p.m. ET on Fox.




  • Favorite Returning Show: "Sons of Anarchy"


    "Sons of Anarchy" Season 6 premieres Tues., Sept. 10 at 10 p.m. ET on FX.




  • Favorite Returning Show: "Orphan Black"


    "Orphan Black" Season 2 premieres April 2014 on BBC America.




  • Favorite Returning Show: "The Good Wife"


    "The Good Wife" Season 5 premieres Sun., Sept. 29 at 9 p.m. ET on CBS.




  • Favorite Returning Show: "Arrow"


    "Arrow" Season 2 premieres Wed., Oct. 9 at 8 p.m. ET on The CW.




  • Favorite Returning Show: "Glee"


    "Glee" Season 5 premieres Thurs., Sept. 26 at 9 p.m. ET on Fox.




  • Favorite Returning Show: "American Horror Story: Coven"


    "American Horror Story: Coven" Season 3 premieres on FX.




  • Favorite Stars: Michael J. Fox & Betsy Brandt


    "The Michael J. Fox Show" premieres Thurs., Sept. 26 at 9 p.m. ET on NBC.




  • Favorite Star: Chelsea Peretti


    "Brooklyn Nine-Nine" premieres Tues., Sept. 17 at 8:30 p.m. ET on Fox.




  • Favorite Star: David Walton


    "About A Boy" premieres midseason 2014 on NBC.




  • Favorite Star: Stephen Merchant


    "Hello Ladies" premieres Sun., Sept. 29 at 10:30 p.m. ET on HBO.




  • Favorite Star: Dermot Mulroney


    "Crisis" premieres midseason 2014 on NBC.




  • Favorite Star: Dylan McDermott


    "Hostages" premieres Mon., Sept. 23 at 10 p.m. ET on CBS.




  • Favorite Star: Tom Mison


    "Sleepy Hollow" premieres Mon., Sept. 16 at 9 p.m. ET on Fox.




  • Favorite Star: Lizzy Caplan


    "Masters of Sex" premieres Sun., Sept. 29 at 10 p.m. ET on Showtime.




  • Favorite Stars: Sarah Michelle Gellar (left) & James Wolk (far right)


    "The Crazy Ones" premieres Thurs., Sept. 26 at 9 p.m. ET on CBS.




  • Favorite Star: Clark Gregg


    "Marvel's Agents of S.H.I.E.L.D." premieres Tues., Sept. 24 at 8 p.m. ET on ABC.




  • Favorite Star: Anna Faris


    "Mom" premieres Mon., Sept. 23 at 9:30 p.m. ET on CBS.




  • Favorite Star: Parker Young


    "Enlisted" premieres Fri., Nov. 8 at 9:30 p.m. on Fox.




  • Best New Drama: "Masters of Sex"


    "Masters of Sex" premieres Sun., Sept. 29 at 10 p.m. ET on Showtime.




  • Best New Drama: "Reign"


    "Reign" premieres Thurs., Oct. 17 at 9 p.m. ET on The CW.




  • Best New Drama: "The Blacklist"


    "The Blacklist" premieres Mon., Sept. 23 at 10 p.m. ET on NBC.




  • Best New Drama: "Hostages"


    "Hostages" premieres Mon., Sept. 23 at 10 p.m. ET on CBS.




  • Best New Drama: "Sleepy Hollow"


    "Sleepy Hollow" premieres Mon., Sept. 16 at 9 p.m. ET on Fox.




  • Best New Drama: "Almost Human"


    "Almost Human" premieres Mon., Nov. 4 at 8 p.m. ET on Fox.




  • Best New Drama: "Marvel's Agents of S.H.I.E.L.D."


    "Marvel's Agents of S.H.I.E.L.D." premieres Tues., Sept. 24 at 8 p.m. ET on ABC.




  • Best New Comedy: "Brooklyn Nine-Nine"


    "Brooklyn Nine-Nine" premieres Tues., Sept. 17 at 8:30 p.m. ET on Fox.




  • Best New Comedy: "Enlisted"


    "Enlisted" premieres Fri., Nov. 8 at 9:30 p.m. on Fox.




  • Best New Comedy: "Hello Ladies"


    "Hello Ladies" premieres Sun., Sept. 29 at 10:30 p.m. ET on HBO.




  • Best New Comedy: "Mom"


    "Mom" premieres Mon., Sept. 23 at 9:30 p.m. ET on CBS.




  • Best New Comedy: "Trophy Wife"


    "Trophy Wife" premieres Tues., Sept. 24 at 9:30 p.m. ET on ABC.




  • Best New Comedy: "The Crazy Ones"


    "The Crazy Ones" premieres Thurs., Sept. 26 at 9 p.m. ET on CBS.




  • Best New Comedy: "About A Boy"


    "About A Boy" premieres midseason 2014 on NBC.