Von der Leyen, 60, was born in Brussels and spent her early years in the Belgian capital. She speaks fluent English and French, having studied at the London School of Economics in the 1970s and lived in Stanford, California, from 1992 to 1996.
She was long viewed as a potential successor to Merkel, but has had a tough tenure at the head of the notoriously difficult defense ministry and had long since faded out of contention by the time Merkel stepped down last year as leader of her center-right Christian Democratic Union party.
Still, von der Leyen — a medical doctor and mother of seven — played a significant role in modernizing the image of her party during the Merkel years, over which it dominated the political middle ground. As minister for families in Merkel's first Cabinet from 2005 to 2009, she introduced benefits encouraging fathers to look after their young children.
Von der Leyen then served as labor minister until 2013, when she became Germany's first female defense minister. In that job, she championed greater European cooperation. "Europe won't get ahead in the game of global powers if some discreetly hold back when military deployments come up and others rush ahead without consulting," she said shortly after taking over the defense ministry. She followed that up by declaring that "it's important that Germany takes more responsibility within our alliances — within the European alliance and within NATO."
Shortly after Britain voted to leave the European Union in 2016, she said that Brexit offered the bloc an opportunity to press ahead with greater military cooperation. "Britain consistently blocked everything that had Europe written on it," von der Leyen said. She argued that closer military ties between member states could help ease the frustration many voters feel about the EU's inability to tackle major issues.
In a defense policy review issued at the same time, the government said citizens of other EU countries could be allowed to serve in the German army. In an interview with news magazine Der Spiegel in 2011, as the eurozone debt crisis rumbled, von der Leyen declared a loftier goal for Europe. "My aim is the United States of Europe — on the model of federal states such as Switzerland, Germany or the U.S." She said that Europe could use its "size advantage" on financial, taxation and economic questions.
Von der Leyen has presided recently over increased German military spending, though it still falls well short of the 2% of gross domestic product that the United States wants to see from its NATO partners. Members of the alliance agreed in 2014 to "aim to move toward" increasing defense spending to 2% of GDP by 2024, though Germany has said it doesn't expect to meet that goal.
Merkel said Tuesday that von der Leyen "enjoys great confidence" among European leaders, pointing to her involvement in a NATO force in the Aegean Sea during the migrant influx, Germany's help in patrolling the airspace of Baltic countries and her commitment to Europe.
Von der Leyen comes from a political family and is the daughter of a former governor of her home state of Lower Saxony, Ernst Albrecht, who before that was a senior European civil servant. She has been a deputy leader of Merkel's CDU since 2010. Over the years, she was often talked about as a potential successor to Merkel, though she herself publicly dismissed such talk.
"In every generation, there is one chancellor," she said in 2013. "In my generation, that is Angela Merkel." In her time as defense minister, von der Leyen faded out of speculation about the succession. Inheriting a military in the midst of a massive change from conscription to a professional force, she increasingly had to deal with negative headlines of her own and others' making.
The poor state of the German military's equipment has been a regular issue. Other problems included questions over the appointment of external experts to the military and the ballooning costs of the renovation of a military sailing ship.
Von der Leyen herself irked soldiers in 2017 by declaring that the military had a "problem with its stance" and "leadership weakness at various levels," criticism that followed the arrest of a soldier alleged to have passed himself off as a Syrian refugee and planned to attack prominent political figures then pin the blame on migrants.
Merkel's junior coalition partners in Berlin, the center-left Social Democrats, weren't impressed with the nomination of von der Leyen or the overall package put together Tuesday by EU leaders. Merkel said she abstained in EU leaders' otherwise-unanimous nomination of von der Leyen because of the lack of unity at home.
A former Social Democrat leader, ex-European Parliament president Martin Schulz, tweeted that she "is the weakest minister here."