David Cameron will plead with the British public to stay in the EU to keep peaceful relations between European countries, as he suggests the referendum contest will form a pivotal moment in the continent's history.
The Prime Minister will issue the rallying cry as the EU contest enters a new phase, with both sides stepping up their activities in the run-up to the June 23 vote.
Cameron will stress the long, historic links with continental Europe - and highlight the sacrifice of British military personnel to ensure the peace of the continent as he makes a "patriotic case" for a Remain vote.
Both Cameron and his Tory rival, Brexit-backing Boris Johnson, are set to make speeches this morning as the referendum looms ever closer.
The PM's speech will warn that the peace which Europe has enjoyed in recent years cannot be guaranteed "beyond any shadow of doubt" and ask "is that a risk worth taking?"
He will rank 2016 alongside other turning points in European history including the year of the Spanish Armada in 1588, Blenheim in 1704, Waterloo in 1815, the First World War in 1914, the Battle of Britain in 1940 and the fall of the Berlin Wall in 1989.
"The European Union has helped reconcile countries which were at each other's throats for decades," he will say.
"Britain has a fundamental national interest in maintaining common purpose in Europe to avoid future conflict between European countries. And that requires British leadership, and for Britain to remain a member."
He will add: "Either we influence Europe, or it influences us. And if things go wrong in Europe, let's not pretend we can be immune from the consequences."
Setting out the long ties binding the UK to its neighbours, Cameron will say: "For good or ill, we have written Europe's history just as Europe has helped to write ours."
Cameron is set to appeal to the nation's nostalgia, harking back to pivotal moments in European history including Blenheim, Trafalgar, and Waterloo.
He'll also remember how Winston Churchill "argued passionately for Western Europe to come together, to promote free trade, and to build institutions which would endure so that our continent would never again see such bloodshed."
The Britain Stronger In Europe campaign released a video message from Second World War veterans to underline the Prime Minister's message. Cameron will say: "Whenever we turn our back on Europe, sooner or later we come to regret it.
"We have always had to go back in, and always at much higher cost. The serried rows of white headstones in lovingly-tended Commonwealth war cemeteries stand as silent testament to the price this country has paid to help restore peace and order in Europe."
Highlighting the bloodshed in the Balkans and Russian aggression in Georgia and Ukraine, he will say: "Can we be so sure that peace and stability on our continent are assured beyond any shadow of doubt?
"Is that a risk worth taking? I would never be so rash as to make that assumption."