Upon leaving Hogwarts in 1945, Tom Riddle travels wide and far, sinking deeply into the dark arts in his quest for immortality and power. He undergoes many dangerous magical transformations and consorts with those considered the "worst" of the wizarding world. He reappears in the early 1970s as Lord Voldemort. Few recognise him as Tom Riddle.
He begins to campaign, politically gaining support from all areas of the wizarding community. He promotes keeping muggles out of wizarding business, promises to protect wizarding rights and to consider them over other creatures rights. He intends to take over the Ministry in a similar fashion to the German Nazi party. His party and popularity grows and Voldemort appears to be the next Minister of Magic until in 1980 a group of anti-Voldemort radicals hold a rally against the man and his policies. A group of Voldemort supporters attack the rally, using and abusing Unforgivables. People from both sides are arrested but Voldemort suffers most of all as he is completely discredited. It's widely believed (but never proven) that he put his supporters up to it.
These supporters are soon released through shifty means and Voldemort steps out of politics to take charge of his group (now known as Death Eaters) to go about taking power a different way. All of a sudden, the wizarding world is under attack and the Death Eaters are leading the way! Attacks are staged all over the country, not a day goes by without a list of dead gracing the inside cover of the paper. Voldemort is rarely seen as his minions do most of the work while he gathers strength. To counter the attacks, an opposing faction appears in late 1981, they are led by Nicholas Flamel and Albus Dumbledore. The faction is quick to respond to the Death Eater attacks and the casualty toll grows higher and higher. The opposing faction splits suddenly in 1982, with Dumbledore going off to form the Order. The Order takes a significantly LESS violent approach to the whole thing and concentrate more on capturing those responsible and bringing them to justice.
In 1983, Voldemort starts research into different ways of extending his life. He begins to experiment with the idea of horcruxes and succeeds in splitting his soul six times. In 1987, an informant in Flamel's group informs him of the Philosopher's Stone. Flamel decides to try and upgrade the stone after hearing of new information on the topic, discovered by the Ashworths. The incomplete stone is stolen from Flamel, and he is killed in the process. Voldemort is unaware of the extra work Flamel was going and the stone is unstable and poisonous (the Ashworths had provided faulty information with hopes to eliminate Flamel AND Voldemort). But, unfortunately for them, when Voldemort goes ahead and tries to use it, unaware of any possible consequences, the stone didn't quite get the job done. The stone sapped him of all life and it took him 10 years to restore himself to full strength and a further three years to regain the numbers of supporters that he'd lost over the years. The Ashworths involvement in the entire thing is not well known, very few would be aware of their presense in the entire thing.
During the ten years of his absence, the Death Eaters continued to support him and continued 'preaching his message'. Many were arrested and sent to Azkaban, many simply stopped DE activity and claimed to have been under Imperius. Others have never been captured, with many standing strong together over the years. For the public, the threat of Voldemort's return had never disappeared. The Wizarding community had always been on edge. Dumbledore took it upon himself to track down the horcruxes made by Voldemort over the ten years, and succeeded in destroying four of them. Two are still hidden. The Order had suffered a drop in young members joining as they no longer saw it as a worthy cause. The Death Eater attacks were more seperated and sporadic, they appeared to be dying out.
When Voldemort returned to lead the Death Eaters again it was the year 2000. For the last six years the Death Eaters have worked under cover, slowly working to gain control of all important Wizarding mediums. In late 2005, their presence was felt again as the attacks started up once more and fear was returned to the wizarding community. The Order has slowly grown in numbers since then, but are still much weaker than the Death Eaters. A schism can be seen forming in the Order over what they should be doing about it, many hope that the emergence of the current 7th years (many whom have been directly affected by the war) will strengthen them and return the Order to the strong status it once held.