There are $7.5 trillion traded across the world’s foreign exchange markets every single day. Of that colossal sum, one currency pair — the euro against the US dollar — accounts for more than $1.7 trillion in daily volume. It is the most liquid, most watched financial instrument on earth. For 27 years, it has been both a barometer of geopolitical risk and the world’s most consequential monetary experiment.

No currency in history has been engineered the way the euro was. Not backed by the military dominance of a single empire, not born of colonial conquest, not evolved organically through centuries of commerce — the euro was designed. Designed in treaty rooms by economists and politicians who believed that erasing exchange rates between France and Germany, between Italy and Spain, would deliver the prosperity and peace that two world wars had failed to produce. Whether they were right is a question that 350 million Europeans answer at the petrol pump, the checkout, and the ballot box, every single day.

On March 13, 2026, EUR/USD sits at $1.1524. Down 4.1% from its 2026 peak. Caught between the Iran war’s oil shock and the structural dollar weakness thesis that drove it to $1.2016 in January. Watched by every FX desk on the planet. This is the complete story — and what comes next.

The idea of a shared European currency did not begin at Maastricht in 1992. It began at the end of the Second World War, in the rubble of a continent that had destroyed itself twice in thirty years — when European architects looked at the competitive devaluations and economic nationalism of the 1930s and made a diagnosis: money had been weaponised, and nations that wielded it against each other would eventually go to war because of it.

The Werner Report of 1970 — authored by Luxembourg Prime Minister Pierre Werner for the European Council — was the first serious blueprint. It proposed achieving monetary union by 1980 through coordinated policy, narrowing exchange rate bands, and ultimately a single currency under a common central bank. The OPEC oil shock of 1973, the collapse of Bretton Woods, and the currency volatility of the 1970s killed that timeline entirely. But the intellectual foundations survived.

What finally made monetary union politically possible was the fall of the Berlin Wall in November 1989. When German reunification became inevitable, French President François Mitterrand made a calculation: a unified Germany — 80 million people, Europe’s largest economy, positioned at the continent’s centre — would dominate Europe unless embedded so deeply in shared institutions that its power could only be exercised collectively. The price he negotiated for French support of reunification was Helmut Kohl’s agreement to surrender the Deutsche Mark. It was perhaps the most consequential monetary trade in post-war European history.

The Maastricht Treaty was signed on February 7, 1992. It required all member states to achieve five convergence criteria before joining: inflation within 1.5 percentage points of the three lowest EU rates, budget deficits below 3% of GDP, debt below 60% of GDP, exchange rate stability within ERM bands, and long-term interest rates within 2 percentage points of the three lowest. Germany designed these criteria to ensure its new currency would inherit the Deutsche Mark’s reputation for discipline. Several founding members — most notably Italy with debt at 121% of GDP and Belgium at 130% — were admitted anyway, with the understanding that they were on a convergence path. That decision would almost destroy the euro, eleven years later.

At midnight on January 1, 1999, eleven currencies ceased to exist as independent monetary instruments. The German Deutsche Mark, French franc, Italian lira, Spanish peseta, Portuguese escudo, Dutch guilder, Belgian franc, Austrian schilling, Finnish markka, Irish pound, and Luxembourg franc all became fixed subunits of a new currency whose exchange rates were locked permanently on December 31, 1998. There was no going back. There was no mechanism for going back. That was the point.

For the first three years, the euro was invisible. It existed in ledgers, in computers, in interbank transfers. You could not hold it, carry it, or spend it. Physical coins and notes would not arrive until January 1, 2002. In that strange electronic interregnum, the euro’s opening price was set by market consensus at $1.1747 on its first day of trading — broadly in line with the weighted average of the legacy currencies it absorbed.

Markets were immediately skeptical. The euro’s launch coincided with the peak of the dot-com bubble — a period of extraordinary US equity performance, soaring dollar confidence, and capital flooding into American technology stocks. By October 2000, just 21 months after launch, EUR/USD had fallen to its all-time low of $0.8230 — a 30% loss against the currency it was supposed to eventually challenge for reserve currency dominance. Denmark held a referendum on joining in September 2000 and voted to keep its krone by 53% to 47%. The euro’s credibility was in genuine doubt.

The euro has not moved in straight lines. It has moved in episodes — each one triggered by a specific failure of assumption, a policy miscalculation, or a geopolitical shock that the market had decided to ignore until it suddenly couldn’t. Understanding each crisis’s shape — how fast it fell, what catalysed the recovery, and how long the recovery took — is the single most valuable tool for navigating the current Iran war episode.

EUR/USD is not simply a vote on relative economic health. It is a real-time referendum on interest rate differentials, energy prices, geopolitical risk, capital flows, and the credibility of two of the world’s three most powerful central banks. Traders who reduce it to “strong US data equals strong dollar” will be right 60% of the time and catastrophically wrong the 40% that matters most.

The most powerful short-to-medium term EUR/USD driver. When the Fed funds rate exceeds the ECB deposit rate, dollar assets offer higher nominal returns. Global capital sells euros to buy dollars. The 2022–2023 case was definitive: the Fed raised 525bp while the ECB raised 450bp at a slower pace, the differential peaked at ~150bp, and EUR/USD fell to $0.9535. As the gap narrows — as it has since the Fed began cutting in 2024 — EUR/USD recovers. Today’s differential is approximately 175bp in favour of the dollar. That suppresses the euro structurally until the ECB either hikes or the Fed cuts.

This is permanent and deeply underestimated by non-specialist traders. The eurozone imports 97% of its crude oil and the majority of its natural gas. When energy prices surge — as in 2022 and again in 2026 — Europe faces both an inflation shock and a current account deterioration that weakens the euro directly. The 2022 energy crisis cost the eurozone an estimated €800 billion in additional import costs. The Iran war’s oil shock is applying the same structural pressure. Every $10 sustained increase in Brent costs the eurozone approximately €35–40 billion in annual import bills — money that leaves the continent and lands in dollar-denominated energy markets.

The euro carries a political risk premium no other major currency bears. Its survival requires twenty nations — running fundamentally different economies — to remain committed to a shared monetary policy when individual interests diverge. That premium is priced highest when growth is weakest and peripheral spreads widen. Italy’s debt at 140% of GDP, France’s deficit above 5%, and Greece’s structural fragility mean there is always a non-zero probability that the euro’s political architecture is tested again.

In moments of genuine geopolitical shock, the dollar does not behave like an ordinary currency. It is the world’s reserve, the denomination of oil, and the asset into which global capital retreats when fear is highest. The Iran war has reactivated this mechanism completely. While it persists — while Hormuz remains effectively closed — the safe-haven dollar premium caps EUR/USD rallies regardless of any fundamental analysis. The market’s fear trade always beats the economist’s rate differential model in the short run.

The most powerful long-term driver is the one least discussed on trading desks. The US national debt stands at $36 trillion — 125% of GDP — with annual interest payments exceeding $1 trillion. Global central banks have been steadily diversifying away from the dollar: the US dollar’s share of global reserves has fallen from 71% in 1999 to 56.3% by end-2025. That structural de-dollarisation trend does not move EUR/USD on any given day. Over five-year periods, it has been the dominant driver of every major dollar bear market. It is the clock that the Iran war has temporarily paused — but not stopped.

Six weeks ago, EUR/USD was the consensus long trade across every major FX desk. Goldman Sachs had a year-end 2026 target of $1.25. Deutsche Bank was at $1.25. MUFG had titled its 2026 outlook “A Post-Peak USD World.” The narrative was clean, data-supported, and broadly held: the Fed would cut twice, US fiscal deficits would erode dollar credibility, Germany’s historic €500 billion infrastructure programme would reboot eurozone growth, and the long dollar bull market that began in 2022 was definitively over.

Then February 28 happened. And in thirteen trading days, every one of those targets became a number to revise rather than a destination to target.

The ECB’s position is genuinely difficult. At its February 5, 2026 meeting — three weeks before the war began — the Governing Council held rates at 2.00% for the fifth consecutive time. Lagarde described inflation as “a good place.” Eurozone CPI had fallen to 1.7% in January — below the 2% target for the first time in three years. Markets were pricing a one-in-five chance of a cut before year-end. Now those same markets price an 85% probability of at least one 25bp hike by December.

That shift is not irrational. Every $10 sustained increase in oil adds approximately 0.5 percentage points to eurozone HICP inflation, according to the ECB’s own modelling. Oil is up $41 since February 27, implying roughly 2 full percentage points of additional inflation pressure if current prices hold — enough to push HICP from 1.7% back toward 3.5–4.0%. Oxford Economics maintains the ECB will look through the shock as temporary. Goldman Sachs says the ECB only hikes in the “worst-case scenario.” The market, characteristically, is pricing somewhere in between.

The following short-term projections represent Capital Street FX Research Desk’s independent analysis, incorporating the Iran war’s oil shock, the FOMC meeting on March 18–19, ECB commentary, Hormuz developments, and the technical structure of EUR/USD’s current pullback. These are not consensus views. They are our proprietary assessment.

The current setup is not a clean momentum trade in either direction. EUR/USD is pinned between two forces of roughly equal magnitude: the Iran war’s dollar safe-haven bid pulling it down, and the structural dollar weakness thesis that drove it to $1.2016 in January pulling it back up. In environments like this, the optimal trade is not a directional bet with reckless leverage — it is a position with a defined entry zone, a clearly articulated reason the floor holds, a generous stop below the structural support, and targets calibrated to the probability-weighted scenario.

Euro banknotes, Europa series · The physical currency that 350 million Europeans have used since January 1, 2002 · ECB / Wikipedia