TONIGHT's Oscars are set to come wrapped in black, in the angry, mournful gowns of the #MeToo protest. But this is just one sign of the level of politics that has always surrounded the awards - from the winners, the speeches, and the movies, the Oscar ceremony has always reflected the zeitgeist, what worries us, and the events in the world. Because who takes home the big gongs says a great deal about global culture, the political moment the United States is in, the way the western world sees itself, and how society is changing.

For instance, this year’s best director Oscar nominees are the most diverse they have ever been. The award, notably, could go to a black man for Get Out, a director who has made a film starring a trans-woman, A Fantastic Woman, and, yes, a woman, for Lady Bird.

That a woman is up for the award matters. It particularly matters in the year of #MeToo, in which the dark underbelly of Hollywood has been exposed. Greta Gerwig’s coming-of-age tale, her directorial debut Lady Bird, is up for five awards, including Best Picture and Best Director. She is just the fifth woman to be nominated for the latter award. We can pretend that the Oscars aren't political, that they are purely about art. But that has never been true. They have always reflected their times – as this brief history shows.

All Quiet On The Western Front, 1930

The ultimate anti-war film - made by the 'Lost Generation' that fought in World War I - took the Best Picture Oscar at a time when war films were patriotic not pacifist. Based on the 1929 novel by Eric Maria Remarque, this film showed war at its most dehumanising, devoid of heroism. It was so controversial that a multitude of different versions existed in an effort to deliver it to the widest possible audience, without offending them. Nevertheless some did still walk out. It was banned in Germany, where Nazis interrupted screenings, and, allegedly, let loose rats in the theatres - Goebbels denounced the film. Ironically, it was a version of the film that Goebbels had kept which was used when a reconstruction aired on West German television in 1984. Its star, Lewis Ayres, became a conscientious objector in World War II

Gone With The Wind, 1939

These days it’s not uncommon to object to, or ban, screenings of Gone With The Wind, as was done last year in Tennessee, for being “racially insensitive”. But this was the film that swept the board at the 1939 Oscars and which showed Southern ways, including slavery, in a positive light at a time of the Jim Crow laws which enforced racial segregation in the Southern States. Notably, Hattie McDaniel received the award for Best Supporting Actress, the first black actor to ever receive an Oscar. But the restrictions on her at the time speak volumes. She was not allowed to attend the premiere because of her colour. And she was only allowed at the Oscars themselves because the Ambassador Hotel, at which they were held, waived its strict 'No Blacks' policy.

The Wizard Of Oz, 1939

The world was on the brink of war, but also among the winners in 1939, for Best Music, was “Over The Rainbow”, a song from the Technicolor dream that is the Wizard Of Oz. That award, and its many other nominations, at that year’s awards says a great deal about how much America had fallen for this allegorical piece of escapism. But the film wasn’t without its hints of war – “Surrender Dorothy” says the Wicked Witch of the West – and some interpret the narrative as playing to the question of whether America should just look after itself or get involved in the coming conflict. Just over the rainbow was unspeakable horror, but that year that film enchanted America and later the world. According to the Wizard Of Oz: 75th Anniversary Companion, “We’re Off To See The Wizard" became a World War II battle march, sung by the Australian troops in many of their battles.

Casablanca, 1942

From "Play it Sam" to "We'll always have Paris", we know so many of Humphrey Bogart and Ingrid Bergman’s lines, but what’s often forgotten is that Casablanca – which took home the awards for Best Picture, Best Director and Best Screenplay – was a very effective piece of propaganda cinema, pitched at an American uncomfortable about just committing to another European conflict. Bogart’s Rick Blaine, some say, is the personification of isolationism, who ultimately has to choose a side. After the attack on Pearl Harbor in December 1941, the Office of War Information was set up to promote the war effort, and work as a propaganda agency. They were keen to tap into the power of film and issued specific guidelines, as well as reviewing scripts and early cuts of films. Casablanca, was a triumph on that level. It made America feel emotionally involved.

On The Waterfront, 1955

In 1952 Elia Kazan testified at the House Un-American Activities Committee against fellow communists. On The Waterfront, which won eight Oscars, is widely considered to be the director's response to those who criticised him for that, even his apology, and is thus a story about McCarthyism and what it did to people. Its leading character, longshoreman Terry Malloy, played by Marlon Brando, turns “canary” in the film. Kazan wrote: “When Brando at the end yells . . . ‘I’m glad what I done to you' that was me saying, with identical heat, that I was glad I’d testified as I had.” The film's writer, Budd Schulberg, also named names to the committee.

The Brave One, 1957

Two years after On The Waterfront, the award for Best Story went to Robert Rich, for The Brave One. Only Rich wasn’t the writer’s actual name, but an alias for Dalton Trumbo, who refused to testify at the House Un-American Activities Committee and was therefore blacklisted by Hollywood. Trumbo continued to write under numerous names, while in jail and while in self-imposed exile in Mexico. In 1975, the Academy finally formally presented the award to Trumbo himself, and, more recently Bryan Cranston played him in the 2015 biopic Trumbo.

In The Heat Of The Night, 1968

Racial tensions were boiling over in the United States in the year when the Oscar for Best Film went to a movie starring Sidney Poitier as an African-American police detective, arrested on suspicion of murder by his racist chief, played by Rod Steiger. This was the year when Martin Luther King made his “I’ve been to the mountain top” speech. The Detroit race riots took place in the summer of 1967. The Kerner report, published later that year, declared: “Our Nation is moving toward two societies, one black, one white – separate and unequal.” Days before the Academy Awards King was assassinated. Riots erupted across the country. Poitier and others were scheduled to perform at the event, but cancelled, and then the organisers agreed to reschedule, pushing the event back two more days. It was Rod Steiger, however, not Poitier, who won the Oscar for Best Actor

Midnight Cowboy, 1970

It says a lot about its times that Midnight Cowboy, with its transgressive exploration of sexuality, is the only X-rated film to have won an Oscar, especially when you look at the list of winners that came before it – Oliver!, The Sound Of Music, My Fair Lady, A Man For All Seasons. Many critics see director John Schlesinger’s tale of a young Texan, played by Jon Voight, crashing into liberal New York, experimenting with working as a gigolo to rich housewives and gay sex, as being the moment the Academy recognised the shift from Old Hollywood to the new auteur director generation. But it’s also remarkable because it carried all the swing of the sixties. The Stonewall riots had taken place the year before. Midnight Cowboy told a story of this new America.

The Godfather, 1973

Both the Mario Puzo novel and the Francis Ford Coppola film questioned the legitimacy of power and proposed the idea that “behind every great fortune lies a great crime”. It was released in the year of Watergate and the end of the Vietnam war. Dramatically, Marlon Brando also declined his Oscar in support of Native Americans. Instead of appearing himself, he sent on a woman in Native American dress, who spoke for him.

One Flew Over The Cuckoo’s Nest, 1976

Although a film no studio wanted, this adaptation of Beatnik icon Ken Kesey’s book, starring amongst others, Jack Nicholson and Louise Fletcher, took home the big five awards at the Oscars that year. The tale of a free-spirited rebel locked in a psychiatric hospital expressed the spirit of its time. It was non-conformist, revolutionary and reflected the post-Vietnam, post-Watergate distrust of power. Fletcher, who won Best Actress, based her notion of Nurse Ratched on Nixon. She has said: “At the time, Watergate was very big in my life. I was outraged by what was going on. I just took the belief that absolute power corrupts. Nixon was convinced that he was doing what he ought to be doing, and never mind who got hurt in the meantime. I believed that [Ratched] was convinced that she was doing the right thing.”

Kramer vs Kramer, 1979

Divorce had begun to rocket during the 70s and Meryl Streep and Dustin Hoffman battling it out in court for custody of their son said everything about how gender politics and family life had changed. Here was the story of the impact of second wave feminism, but also the backlash against it – for Meryl Streep’s character is a woman abandoning her family. Streep, famously, however, rewrote her lines undermining the anti-women's lib message.

Forrest Gump, 1994

Forrest Gump tops several lists for best conservative film – though this may not have been its makers' intentions. Many saw in the Clinton-era hit a celebration of a return to American family values and an attack on the counterculture. Newt Gingrich, the Republican Speaker of the House, at the time was even a fan. He said, at a Republican women’s group, “in every scene of the movie in which the counterculture occurs, they’re either dirty, nasty, abusive, vindictive, beating a woman or doing something grotesque. It’s important to remember that in that period, Bill Clinton was on the side of the counterculture”. During his Academy Award acceptance speech, producer Steve Tisch said: “Forrest Gump isn't about politics or conservative values. It's about humanity. It's about respect, tolerance and unconditional love.”

Milk, 2009

In November 2008, California voters approved Proposition 8, banning same-sex marriage, and caused an outcry from its opponents. This made the Oscars for Milk seemed all the more pertinent, and when Sean Penn picked up his award for portraying slain gay rights icon Harvey Milk, he said: “I think that it is a good time for those who voted for the ban against gay marriage to sit and reflect and anticipate their great shame and the shame in their grandchildren’s eyes if they continue that way of support. We’ve got to have equal rights for everyone.”

Selma, 2015

The year of the 50th anniversary of Selma, Martin Luther King's march for voting rights for blacks, brought with it the release of a biopic on the civil rights activist. In January 2015, Barack Obama’s White House hosted a private viewing with the stars as guests. But the film was nominated for few Oscars. The hashtag #OscarsSoWhite trended in the US. The one Oscar the film did take home went to John Legend and rapper Common for Best Original Song. Legend, in his speech, spoke on voting rights as well as mass incarceration, citing that there are "more black men under correctional control today than were under slavery in 1850".

Moonlight, 2017

After years of controversy over the 'whiteness' of Oscar nominees, the awarding of Best Picture to Barry Jenkins’ Moonlight – a low budget film about a gay black man coming of age – felt like a moment in which the Academy came good. As one critic put it: “It isn’t the first best picture winner (Steve McQueen’s 12 Years a Slave achieved that milestone four years ago), but it was the first to do so without being about civil rights or race relations – which is also a milestone.”