The keel-laying ceremony for the Virginia-class boat took place at the downtown shipyard with officials and a crowd of some 300 dwarfed by a large bow section of the sub, draped in blue.
The highlight came when welder Lawrence "L.A." Britt burned the Second Lady's initials into a steel plate that will become part of the vessel.
Then Biden declared the keel to be "truly and fairly laid."
The ceremony symbolizes the start of construction, but in fact the Delaware is already about 56 percent complete. It is scheduled for delivery to the Navy in late 2018.
Biden's role as ship's sponsor will offer a different window into the lives of military families, which has been a major focus of her tenure as second lady.
Five years ago, she teamed with first lady Michelle Obama on the Joining Forces initiative, which challenged Americans to support the families of U.S. troops.
As a ship's sponsor, Biden will add the 135 crew members of the Delaware to her own extended family. A sponsor is considered an honorary member of the crew and often interacts with officers and sailors. It will also give Biden entry into the submarine community, a close-knit group that lives by its motto, "the silent service," often foregoing the publicity that comes with other forms of Navy service, such as being a fighter pilot or serving on an aircraft carrier.
Vice Adm. Joseph Tofalo, commander of Navy submarine forces, said Biden's sponsorship was especially appropriate given her focus on military families, which is also a form of silent service.
"Our family members, just like a submarine, are often on scene, unseen," he said, "doing work that nobody else can do, enabling our military personnel to do their very demanding jobs."
The Delaware's crew has started to arrive and now stands at 48 sailors. As they sat in the audience, Biden addressed them directly.
"You represent 27 states," she said. "Many of your spouses and children -- almost 60 kids -- are stationed with you in Virginia. Eighteen of you attended community college."
That last point is a source of pride for Biden, who teaches English at Northern Virginia Community College in addition to her duties as second lady.
"Getting into submarine service is not easy," she said. "You have to understand complex systems and undergo intense training. As a community college teacher, it's always great to see when community college students go on to do exceptional things."
As the ship's sponsor, Biden will break a bottle across the ship's bow at its christening. She will call the crew on board for its commissioning into the Navy fleet. But true to her focus, she also looks forward to meeting the families that support the crew.
She noted that the family of Delaware's commanding officer, Cmdr. Brian Hogan, has moved 12 times during his career -- and that's not uncommon. Having a strong family support system makes that lifestyle easier to bear.
"Behind every sailor is family -- the spouses, the children, parents, grandparents and friends," she said.
Accompanying her to Newport News was grandson Hunter Biden, the son of the late Beau Biden.
Beau, the elder son of Vice President Joe Biden, was considered a rising star in Delaware when he died last year of brain cancer. He was a member of the Delaware National Guard and served as a major in the Judge Advocate General's Corps. He served a tour in Iraq in 2008 and received the Bronze Star.
Also speaking at the ceremony was Rep. Randy Forbes, R-Chesapeake, who noted the importance of Virginia-class subs to the Navy fleet. Forbes chairs the sea power panel of the House Armed Services Committee, and is looking to maintain the two-per-year production rate of the vessels even as the Navy prepares to build a new fleet of larger, ballistic missile submarines.
Virginia-class attack submarines are built in a teaming arrangement between the Newport News shipyard, a division of Huntington Ingalls Industries, and General Dynamics Electric Boat of Groton, Conn.
The two yards assemble components of the sub, then take turns in final assembly and delivery to the Navy. The Delaware represents the work of more than 4,000 shipbuilders.