He ended it at 2 a.m., saying Republicans had agreed.
It was one of the longer filibusters in history, clocking in ahead of Sen. Rand Paul's (R-Ky.) 13-hour 2013 filibuster on drones and short of Sen. Ted Cruz's (R-Tex.) 21-hour filibuster the same year on Obamacare. (A reminder on the rules: Senators conducting an old-school talking-style filibuster cannot sit, even when someone else is speaking, or eat or even leave to use the bathroom.)
Here are four big moments from the filibuster:
1. It appears to have ended successfully
Which is actually kind of rare in modern-day filibusters. As Murphy wrapped up his seizure of the Senate floor, he said he was closing down shop because Senate Republicans had agreed to allow votes on the two gun-control measures.
That's very different from actually getting those things into law, mind you. Both these proposals — the terrorist watch list and background checks — have been voted on in the Senate in recent years, and both have failed. The Washington Post's Karoun Demirjian reports that as Murphy was talking, backroom negotiations on a compromise on the terrorist watch list were fraying.
And it doesn't seem like House Republicans are keen on taking up either piece of legislation:
But still, Murphy can claim some sort of success by asking for an actionable item (as opposed to conducting a filibuster in protest of something (cough, Rand Paul, and cough, Ted Cruz) and, after nearly 15 arduous hours, getting it.
2. The 35-plus senators who joined him
Around 8 p.m., Murphy looked up into the gallery and waved at his family, who had come to the Capitol to watch him speak, telling his young son by way of explanation that he wasn't planning on seizing the Senate floor for an untold number of hours.
"I decided to do this essentially that morning," he told CBS on Thursday, "and over the course of the day, organically, almost every single Democratic senator decided to join me."
For a spur-of-the-moment event, Murphy's filibuster sure attracted a lot of support from his colleagues, an indication of how united Democrats are on the issue. When your Fix author went to bed Wednesday night, she and C-SPAN cameras counted 37 senators having walked onto the floor to join Murphy, almost all of them Democrats, almost all of them in support of his filibuster.
Shortly before 8 p.m., Senate Minority Leader Harry Reid (D-Nev.) sent out a statement calling Murphy's filibuster "courageous."
By 10 p.m. or 11 p.m., it seemed like every few minutes the doors to the Senate floor were swinging open and a new senator was walking in to help Murphy use up time on the floor, including powerful Democratic leaders such as Sens. Richard J. Durbin (Ill.) and Charles E. Schumer (N.Y.), who gave their own speeches on the need for gun-control laws and asked Murphy softball questions such as: How would banning people on the terrorist watch lists save lives? (I'm paraphrasing there, but you get the point.)
3. And one Republican*
This happened earlier in the day Wednesday, but it's still worth noting. Sen. Ben Sasse of Nebraska — you'll remember him as the Senate's only confirmed #NeverTrump guy — came to the floor, not in support of the gun-control legislation Murphy was asking for but to engage Murphy in some actual debate about it:
Sasse is 1st GOP Senator to question Dem gun filibuster: "I do not know about a comprehensive terrorist list. What is due process here?"— Benny (@bennyjohnson) June 15, 2016
In other words, Sasse wanted to know what Murphy was referring to when saying "terror watch list" since there's actually not just one. (There's several, including a no-fly list, but it's hard to pin down exactly how many since the FBI doesn't willingly share those numbers.) Sasse also asked Murphy to talk about due process of banning people on these lists from buying guns, a major sticking point right now between Republicans and Democrats.
Apparently Twitter lit up, thinking Sasse was on the floor in support of the gun-control legislation, which he quickly had to clarify:
*Sen. Pat Toomey (R-Pa.) came to the floor to speak in favor of some of the proposals, a story we're writing shortly!
4. The filibuster's final moment
It's fair to say both sides of this debate would agree that one victim of gun violence is one too many. But throughout the filibuster — and the whole gun debate, really — Democrats highlighted the emotional pain of gun violence to make their case for more gun-control laws. (Since joining the Senate in 2013, Murphy has given 45 speeches on the floor sharing stories of victims of gun violence.)
As a weary Murphy wrapped up his filibuster around 2 a.m., he shared one more heartbreaking story: that of Dylan, a 6-year-old boy who was murdered along with 25 others at a leafy elementary school in Newtown, Conn., in 2013. First responders found Dylan in his teacher's arms.
Murphy addressed the moment to his son, who was apparently still up in the gallery.