This is a tentative timeline for the thing, probably with too much meaningless points in it but it can be shortened later! It's pretty simply just 'things go from bad to worse'.

[hider=Tentative Timeline]
TIMELINE:
[u]1981[/u] 
– Godric's Hollow is attacked. Lily and James Potter are killed along with their son, Harry, the supposed target of the prophecy.
– The Longbottoms are also personally attacked by Voldemort in the early hours of the morning. None survive.

[u]1982[/u]
– Prophecy revealed by the Dark Lord to followers and, as a result, the magical world as a whole.
– Dumbledore appeals to the International Confederation of Wizards for aid. Refused.
– Morale begins to dwindle; many more purebloods join the Death Eaters.
– Violent attacks on various Wizarding villages increase tenfold.
– Minister Bagnold resigns due to vote of 'No Confidence'. Replaced by Fudge.

[u]1983[/u]
– Hogwarts enrollment drops by 1/4th for the first time since the Second World War.
– Most violent raid on Diagon Alley (thus far). Many shops remain empty even after the battle.
– Auror Department destroyed in explosion, killing 20.
– Azkaban broken into for the first time.

[u]1984[/u]
– Trials of captured Death Eaters begins. None prosecuted.
– Aurors given permission to use Unforgivables in combat.
– [b]Book of Names stolen from Hogwarts. Many Muggleborns lost.[/b]
– Minister Fudge resigns due to vote of 'No Confidence'. Replaced by Lucius Malfoy.

[u]1985–1989[/u]
– Two Muggleborns enrolled in Hogwarts, the lowest number since records began. No more attend.
– No teacher of Defense Against the Dark Arts at Hogwarts.
– Many students drop out to help the war effort on both sides.
– Continuous attacks on various Muggleborn and occasionally Half-Blood homes.
– [b]Civilians given permission to use Unforgivables in combat.[/b]
– Umbridge sent into Hogwarts; several teachers fired including McGonagall.

[u]1990[/u]
– Vigilante raid by the Order of the Phoenix on Malfoy Manor. Minister is assassinated. Minister Rodolphus Lestrange takes over.

[u]1991[/u]
– Ministry officially comes out in support of the Dark Lord.
– Nicholas Flamel and wife are killed. Philosopher's Stone stolen by the Dark Lord.
– Order of the Phoenix forms several splinter groups due to internal conflict, including the first whispers of 'The Ashes'.
– Slytherin House has double the number of residents of Gryffindor and Hufflepuff combined.

[u]1992 – 1995[/u]
– [b]Muggleborn Registration Act signed, the movement spearheaded by Bellatrix Lestrange.[/b]
– Azkaban raided. Sirius Black killed. 12 Grimnauld Place inherited by Draco Malfoy.

[u]1996[/u]
– Wards on Grimnauld Place broken in a surprise attack with many casualties. The Order moves to the Burrow.
– [b]Hogwarts taken over by Voldemort during the summer. Teaching in Hogwarts stops.[/b]

[u]1997[/u]
– Britain's borders close through official channels.
– The Burrow is destroyed and the Order scattered.
– [b]Horcruxes discovered. The Ashes begin to hunt them down.[/b]

[u]1998 – Present (1999)[/u]
– [b]Albus Dumbledore dies. The Ashes rise up to fight against Voldemort.[/b]
– People of varying blood status begin to disappear. Unknown.
[/hider]