FOUR years ago Barack Obama made history when he was sworn in as the 44th – and first black – President of the United States.

The crowds which thronged Washington to witness his inauguration that day were immense. An estimated 1.8 million people took to the streets, many, if not most, overcome with emotion.

The sense of excitement and the desire for hope and change – the promises which had carried him to victory over George W Bush – were palpable. A mood of celebration swept America.

He entered his second term with a sense hanging over him that he has not achieved enough since then. That the hope faded. That his first four years amounted to a wasted opportunity.

Yesterday's inauguration speech was an attempt to scotch that myth and go much further. In 18 short minutes Mr Obama reminded Americans why they handed him a second, decisive election victory and he appealed for their support in the battles that lie ahead.

Four years ago US troops were engaged in bloody conflicts in Iraq and Afghanistan while at home the economy was deep in crisis. Yesterday, however optimistically, he was able to pronounce: "A decade of war is now ending. An economic recovery has begun. America's possibilities are limitless."

Mr Obama believes those possibilities can only be realised if America becomes a fairer society. It is a belief that has made him a hate figure for the Republican right, which seeks to portray him as a dangerously subversive socialist. His challenge in realising his vision is to overcome the political gridlock that caused Republican control of the House of Representatives.

Four years ago he appealed to his opponents to work with him to achieve a "unity of purpose" in Washington.

Yesterday, those words having fallen on deaf ears, he challenged his opponents to defy him. He called for greater equality for women and gay people and improved rights for immigrants workers, linking his plea to Thomas Jefferson's words in the Declaration of Independence – that all are created equal.

He spoke of the need for gun control, making a moving reference to the Newtown massacre. He demanded education reforms and warned of the danger of climate change, saying America would "betray" its children if it failed to lead the race for sustainable energy.

He acknowledged the need to tackle the US's trillion-dollar deficit and bring down health care costs – but he was staunch in his defence of health care, insisting: "We, the people, understand that our country cannot succeed when a shrinking few do very well and a growing many barely make it."

"We, the people ..." he said over and over. "Together ..." he repeated throughout.

Mr Obama will flesh out detailed policy in his State of the Union address next month. But, as a second-term President with time running out, his strategy now seems clear. He will seek to pressure his Republican opponents by appealing over their heads to the people who backed his vision and elected him. It is to be hoped he succeeds. Mr Obama's place in history is assured but a greater legacy to his country and the world is still possible.