“The shot heard round the world.” That’s how history remembers that fateful day in April 1775 when Massachusetts militia engaged British regulars on the fields of Lexington and Concord in defence of their liberties. Brexiteers recall their own summons to freedom, 30 years ago today: Margaret Thatcher’s Bruges speech.

Mrs. Thatcher’s critique of the European Union’s appetite for power made its mark and sparked a movement. Bruges gave birth to Brexit; its apotheosis, the June 2016 referendum vote whether to regain lost sovereignty or to stay within the EU. “Only” the hard work of negotiating Britain’s secession remains.

So much of the Bruges speech informs the rise of Brexit. And with Britain’s withdrawal from Brussels merely six months away, Mrs. Thatcher’s vision can lay the framework for Britain post-Brexit: “the willing and active cooperation between independent sovereign states.”

When the prime minister took to the stage at the College of Europe in September 1988, it must be remembered, she was not a cynic, even while skeptical of the intentions of Brussels’ bureaucracy. She came to “speak of Europe’s future,” Mrs. Thatcher said, for “we British are as much heirs to the legacy of European culture as any other nation.” She did not seek an “isolated existence on the fringes of the European Community.”

Said Mrs. Thatcher at that time: “Our destiny is in Europe.”

Likewise, though, Mrs. Thatcher had an eye toward the legitimacy of the nation state. “That is not to say that our future lies only in Europe,” she reminded her audience, “but nor does that of France or Spain or, indeed, of any other member.” (No. 10’s current occupant, Theresa May, reflects this sentiment when she says that Britain “voted to leave the EU, but not Europe.”)

We also hear echoes of Pitt the Younger who, in the middle of an uncertain contest against Napoleon and Continental dictatorship, encouraged supporters to “hope that England, having saved herself by her energy, may save Europe by her example.”

Many of these nation states still heed Mrs. Thatcher’s example. Austria, for one, remembers her warning about “the erosion of democracy by centralization and bureaucracy” and her “alternative view of Europe’s future.” Frustration with the EU program of central control is inspiring Brexit clones to spring up all over Europe.

Mrs. Thatcher talked of many things at Bruges. The mediæval heritage of Britain and Europe. Two world wars to defend civilized society. The future of defense in the Cold War era. Even of the United States, whose “European values have helped to make [it] into the valiant defender of freedom which she has become.”

Of immediate interest for Brexiteers, during EU withdrawal and for Britain’s future, was Mrs. Thatcher’s impassioned defense of freedom. “The lesson of the economic history of Europe,” she said, “is that central planning and detailed control do not work and that personal endeavor and initiative do.”

Constitutional federalists will recognize the Iron Lady’s fears. The Framers had intended a general government of limited and enumerated powers, accountable to the people for the power it wielded. It was the model for the original EU body. But this frame was based on a feint. The intent less “united” states than a “super” state.

The writing was on the wall from the beginning but it took a politician of Mrs. Thatcher’s stature to read the cypher. “Working more closely together does not require power to be centralized in Brussels or decisions to be taken by an appointed bureaucracy,” she countered. “Success depends on dispersing power and decisions away from the center.”

Events belied the true motivations behind the EU project. Regulatory burdens and constraint on trade, dictated from “above.” For Britain, having shaken off the “sick man of Europe” syndrome of the 1970s through the rigors of privatization, competition, and innovation, it was an insidious chimera.

“We have not successfully rolled back the frontiers of the state in Britain,” Mrs. Thatcher inveighed, “only to see them re-imposed at a European level with a European super-state exercising a new dominance from Brussels.”

This was the essence of her Bruges speech. It is the essence of Brexit. Self-determination. Freedom.

Much like America’s struggle for independence, Britain’s efforts to regain full sovereignty have been arduous. “These are the times that try men’s souls,” wrote an eighteenth-century U.S. patriot, Thomas Paine.

At Bruges, Margaret Thatcher foresaw the constant obstacles in Britain’s path toward freedom, and knew that success in battle depends on steadfast devotion. “Let us never forget that our way of life, our vision and all we hope to achieve, is secured not by the rightness of our cause but by the strength of our defense,” the Iron Lady intoned. “On this, we must never falter, never fail.”

Yet Mrs. Thatcher included a warning that each member of Europe must pay a fair share of the defense costs. So it would not be too much to suggest that at Bruges she signaled not only the independence of Britain but sounded one of the themes of the campaign that gave rise to President Trump.