The Global Resource Wars.

The Resource Wars were a series of global conflicts beginning with the war between the European Commonwealth and the Middle East in April 2052 and ending with the Great War on October 23, 2077. Some of the conflicts included the annexation of Canada by the United States and the Chinese invasion of Anchorage, Alaska.

TimeLine. 

2052 April:

The Resource Wars begin. As many smaller nations go bankrupt due to rising energy prices caused by limited supply, Europe, dependent on oil imports from the Middle East, responds to rising oil prices with military action. Chinese geologists and petroleum exploration engineers work to tap the last remaining oil fields deep beneath the Pacific Ocean, but these efforts are sabotaged by American spies, paving the way for the U.S. energy company Poseidon Oil to claim the resource and erect an oil rig of their own. China will eventually retaliate by invading Alaska in 2066, where the Anchorage Front Line becomes the first and most important battlefield.
May-July: The United Nations, already suffering, begins to collapse. In a series of heated debates, many nations withdraw from the organization as the U.N. tries to keep the peace. On the 26th of July, the United Nations is disbanded.

2053 December:

A terrorist Nuclear Device is used to Destroy Tel-Aviv Europe denies involvement.

2054 January:

Limited nuclear exchange in the Middle East raises fears throughout the world and sets the United States' Project Safehouse in motion. By the end of the Month similar projects have been started in most countries around the world.

2059 March:

The Anchorage Front Line is established, as the United States increases its military presence in Alaska to protect its oil interests. The United States attempts to place pressure on Canada into allowing American military units to guard the Alaskan Pipeline. Naturally, this raises tensions between both countries. Soldiers from the United kingdom are also deployed at key bases Canada to aid in the movement of American Units

2060 June:

The Euro-Middle Eastern War comes to an end as the oil fields in the Middle East run dry. The reasons behind the war are forgotten as both sides are reduced almost to ruin. The European Commonwealth dissolves into quarrelling nation states, fighting over the remaining resources.

2061 January:

British troops are posted all across the south coast of England as Fighting continues across Europe

2066 September:

China, incensed by the United States' takeover of the Alaskan Pipeline fourteen years earlier, invades Alaska. The Anchorage Front Line becomes a true battleground.

2066 October:

Tension between the United States and Canada are rising as Canada is reluctant to allow American troops onto Canadian soil or to allow American planes to fly over Canadian airspace. Canada eventually backs down, however, and U.S. troops pass through Canada. This sets the stage for the Canadian annexation in 2076. Around this time large waves of European refugees begin attempts to cross the channel from France to gain Entry to the United kingdom most are shot before reaching the English Coast line .

2067 February:

The first suits of T-45d power armour are deployed in Alaska. While lacking the full mobility of future versions, its sheer power proves to be incredibly effective against Chinese infantry. Its ability to carry heavy ordnance is key in dominating various localized conflicts, and it has the power to destroy entire towns without endangering the wearer. China rushes to create its own versions, but their technology is many years behind the United States.

2067 March:

British troops lands on the Beaches at Dunkirk and with use of T-45d power armour they set up a Defensive line and stop the flow of Refugees, British troops are ordered to shoot on sight

2069:

The U.S. military presence in Canada and its increasing consumption of resources for the war effort starts to take its toll on the country. Vast stretches of timberland are destroyed, and other resources in Canada are stretched to the breaking point. Many Americans refer to Canada as Little America, and Canadian protests go unheard.

2072 September:

Amid a growing number of protests and riots in several Canadian cities, a group of fanatical citizens attempt to break in and sabotage the Alaskan pipeline. Provoked by these events, the U.S., which has been secretly planning to annex Canada for five years, sets a plan in motion to make it official.
September-December: Completed B.O.M.B. (Ballistic Orbital Missile Base) missiles are sent to different space centres around the U.S. so that they can be carried into space and installed into the B.O.M.B. satellites. The process, though slow, is being carried out fairly regularly. Over the next 5 years

2073 September:

As China becomes increasingly aggressive with their use of biological weapons, the United States government feels that a countermeasure is needed. The Pan-Immunity Virion Project (PVP) is officially formed. Plans are made to begin experiments at the Main West-Tek research facility in Southern California. Aswell as several research stations in the United Kingdom.

2074 March 21st:

Negotiations concerning oil between the U.S. and other world powers comes to a dramatic end. After a much-heated debate, the President storms out of the meeting, later issuing a statement declaring that the last known supply of oil in the world will be used exclusively by the U.S. and that the U.S. will not sell or trade any oil to outside parties.

March 26th:

After Days of heated negotiations Between the US and the UK The special Relationship Breaks Down with a large portion of its Army now stranded in Alaska the UK Begins to fall to rioting

March 27th:

The government of the UK deploys over a thousand Robco Securitrons to restore order, almost a million civilian casualties are recorded along with around 10 thousand Deaths

2074 APRIL:

Contrary to their claims of seeking only to retake Alaska from the Chinese, American power units, infantry, and mechanized divisions are deployed to China. However, they become bogged down on the mainland, putting a further drain on American resources and supply lines.

2075 February 14th:

Understanding that they have been nearly taken over by U.S. troops, Canada finally agrees to be annexed

2076 January:

The United States' annexation of Canada is complete. Canadian protesters and rioters are shot on sight, and the Alaskan Pipeline swarms with American military units. Pictures of atrocities make their way to the United States, causing further unrest and protests.

2076 March 30th:

The President of the United States orders the Pacific Fleet to the Poseidon deep sea oil derrick located at a secret location out in the Pacific.
June: The T-51b power armor is invented. This will prove to be the pinnacle of power armour technology before the Great War. Many of these units are deployed to China, and they begin to carve a swath through the Chinese forces. The Chinese resources are strained to the breaking point, and the supply lines from the nations China has annexed begin to break down.

2077 January 10th:

The United States succeeds in reclaiming Alaska and, along with it, the Anchorage Front Line.
January 22nd: Power armour is first used within the United Kingdom for crowd and quarantine control. Units that had originally served in France and on the Anchorage Front Line find themselves fighting Civilians at home. Riots over scarcity of food increase, and many civilians are killed. Several soldiers attempt to escape, but are captured and sent to military prisons.
March: Prepared for a nuclear or possibly even biological attack from China, the U.S. President and the Enclave retreat to remote sections around the globe and make contingency plans for continuing the war.

2077 October 23rd:

The Great War begins, after China with their back against the wall decide to fire the first weapon. At 14:42 air raid sirens sound throughout cities across the UK, very few people escape into the Vaults under the belief that it is a false alarm. The Vaults are all sealed By 15:01 and only 2 hours after the first strike hits, the world falls silent and is plunged into nuclear winter.