Max Pearson presents a collection of the week's Witness History episodes.

It's 50 years since Richard Nixon became the first US president in history to resign, following the Watergate scandal.

To mark this anniversary, we're featuring first hand accounts from major moments in US presidential history.

We start with the first ever presidential television debate. In 1956, the Democratic and Republican candidates sent female representatives. They were Eleanor Roosevelt and Margaret Chase Smith.

Our expert guest, Dr Kathryn Brownell, from Purdue University in Indiana in the US, discovers other key television debate moments in presidential history.

Then, we hear about the rise of the religious right in America, exploring the emergence of the Moral Majority in the late 1970s.

Following that, we look at one of the closest and most contested elections in history, as Al Gore went head-to-head with George W Bush in the battle for the White House in 2000.

Finally, we hear from the photographer inside the Situation Room as the US closed in on terrorist Osama Bin Laden in 2011.

Contributors: Tom DeFrank - Journalist. Dr Kathryn Brownell - Associate professor of history at Purdue University. Kate Scott and Janann Sherman - Historians. Richard Viguerie - One of the founders of the Moral Majority. Callie Shell - The official photographer for Al Gore's presidential campaign. Pete Souza - Chief Official White House Photographer during Barack Obama's presidency.

(Photo: Richard Nixon waves after becoming the first US president to resign. Credit: Bettmann / Getty Images)