Photo: AMC

Once upon a time, Sterling Cooper was just a scrappy, one-floor ad agency started with seed money from Bert Cooper’s sister Alice. (Alice Cooper. Yep.) And look at ‘em now! Roger, Don, and the other surviving members of the squad are now in “advertising heaven” at McCann Erickson. Or at least that’s what the McCann guy thinks. How did we get here? Journey with us through the long, tortured history of the agency — agencies? — we know and love.

Don is made partner at Sterling Cooper.

Back in season one, everything was peachy: Everybody worked at Sterling Cooper, and all was right in the world. (Except for all the racism and sexism and general oppressiveness.) Then, in season one, episode 10, “Long Weekend,” Roger has a heart attack. Bert tries to rush him back to work in the following episode, “Indian Summer,” but Roger winds up back on a gurney being wheeled out of the office. So Bert decides to promote Don to partner: “I’m not adding your name to the masthead, I’m restoring faith to our clients,” he tells Don. And part of that promotion involves Don being able to appoint a new head of accounts. Another part involves Don declining a contract. That’s his move.

Don hires account man Duck Phillips.

Meet Duck Phillips. Ooooh, Duck Phillips, we rue the day you ever entered our lives. Somewhere out there, Chauncey the dog rues it along with us. Don hires Duck in “Nixon vs. Kennedy,” much to Pete’s irritation, and Duck seems like a good fit for a while. Heck, he’s the guy who brings in Kodak for the famous meeting in “The Wheel.” And for much of season two, things chug along, although Duck’s not a very happy guy, and he has an ongoing issue with feeling undervalued compared to Don. (Join the club, Duck.) He’s also white-knuckling his sobriety, and those feelings all swirl together in season two, episode 11’s “The Jet Set.” Don has vanished in California, leaving Pete high and dry, and Duck takes this as an opportunity to ask for a partnership. Roger turns him down right away, and Duck is pissed. Pissed enough to call up some British colleagues, namely Saint John Powell.

Puttnam, Powell, and Lowe buys Sterling Cooper.

Duck proposes to Powell (of Puttnam, Powell, and Lowe) that the British firm buy Sterling Cooper. “Roger sterling has a 20-year-old fiancée, and his wife’s lawyer’s not going to leave him a pot to piss in,” Duck says, and hey, as long as he’s setting all this up, shouldn’t he be president of the company? Then Duck takes a sip of his room-temperature martini, so we know things are about to get funky.

In “The Mountain King,” the merger moves ahead: Alice encourages Bert to make the deal even though he’s not thrilled about the idea. At this point, the partners are Alice, Bert, Roger, and Don, and Don’s still off in California with Anna, so he doesn’t get to vote. All those in favor say aye. Aye.

Duck tries to become president.

When Don returns from California in “Meditations in an Emergency,” Pete spills the beans on Duck’s semi-secret plan to be agency president. At the big meeting to announce PPL’s plans, Duck acts all surprised to be appointed — “My goodness, obviously I accept” — and Don sabre-rattles a little about quitting. Duck insists he honor his contract, but Don throws back that he doesn’t have a contract, and then a drunk Duck gets all salty and is asked to leave the room. This is the last we see of Duck for a little while!

Don gets the partners fired to avoid going to McCann.

In season three, the merger between PPL and Sterling Cooper is going so-so. There are a lot of layoffs early on — “See you on the breadlines, fellas” says one axed employee — and there’s a bit of culture clash between Pryce’s secretary, Mr. Hooker, and Joan, between Lane and his co-workers, between the British way of doing things and the American way. Guy* having his foot run over by a lawnmower didn’t help, either. But the eventual split comes about very quickly in “Shut the Door. Have a Seat.” Conrad Hilton tells Don that McCann Erickson is poised to buy PPL, and thus Sterling Cooper. Don’s horrified, and in a stroke of genius — well, a stroke of something — convinces Lane to fire him, Bert, and Roger before PPL can be sold.

Why doesn’t Don want to go to McCann? Partially because he believes in the creative work he does, and partially because, well, he’s his own man, darn it, and he’s not just going to be some cog. “There are people out there who buy things, people like you and me. And something happened. Something terrible. And the way that they saw themselves is gone. And nobody understands that. But you do. And that’s very valuable,” he tells Peggy. He’s talking about the Kennedy assassination, but he’s also talking about their personal lives. Don wants to live among the wounded, and he thinks McCann won’t be that.

Sterling Cooper Draper Pryce is born.

And so we have Sterling Cooper Draper Pryce, setting up shop in a hotel room at the end of season three, with a welcomed-to-the-fold Lane adding his name and expertise to the masthead. “Last year our agency was being swallowed whole. I could die of boredom or holster up my guns,” Don brags to a reporter in season four’s premiere, “Public Relations.”

Peggy leaves the agency; Joan becomes partner.

Focus shifts in seasons four and five away from business machinations and to Don’s various domestic horrors. In season four, we see him tool around an awful lot before falling for Faye, and then abruptly dumping her and proposing to Megan. In season five, Don and Megan’s marriage seems to be working out, but then the shadow of death starts descending over the show. Watched week to week, season five’s episodes seemed ominous; watched in a marathon session, it’s a black hole of despair. In “The Other Woman,” Joan sleeps with the Jaguar jag in exchange for a partnership, and just as significant, Peggy leaves the agency to go work for Cutler, Gleason, and Chaough. Betrayal! Except not really: Don had been a real jerk to her for a while, and you can only live for so long in a desperation economy. Ted made her a huge offer, and she accepted. Viva Peggy.

Don ruins SCDP’s chances of going public.

Lane’s death in “Commissions and Fees” doesn’t actually destabilize the agency: In fact, they have their best quarter ever and decide to expand to another floor in “The Phantom.” Everyone feels a little sad and guilty, but hey, they’re rich. Guilt’s tricky like that, though, and it takes a long time for its effects to manifest themselves. It’s not until season six, episode six, “For Immediate Release,” that Don’s turmoil over prostituting Joan seems to fully kick in, and when Herb harasses Megan at a client dinner, Don snaps and dumps Jaguar as a client. Note that this is not at all at Joan’s behest, and she’s in fact furious: There was a plan to try to take SCDP public, and Don’s shenanigans have ruined that as an option. Luckily there’s a chance to win Chevy as a client, so off Don goes to Detroit.

CGC merges with SCDP.

Who should Don bump into at the hotel bar but one Ted Chaough, fresh off an ill-conceived kiss with Peggy. Don and Ted reveal their Chevy pitches to one another, and they admit that neither of their agencies is big enough to impress the client. But what if their two little agencies became One Big Agency? Sold! CGC+SCDP=$. Again we merge. The alphabet soup gets renamed Sterling Cooper and Partners.

Season six closes out with the opening of a California office, though it winds up being more of a headache than an asset. How many marriages did that office ruin? So far two, but who knows what the future holds. First Stan was going to go West, then Don, and eventually Ted — but not before a jittery, half-drunk Don tanks a Hershey’s presentation and gets booted from the firm. In the season-six finale “In Care Of,” the partners vote to put Don on indefinite leave, and he bumps into Duck (Duck!) and Lou Avery on his way out the door. They’re there to replace him.

In season seven, Lou rubs a lot of people the wrong way, and Don’s eventually able to hustle his way back into the firm in “Field Trip,” though with several onerous conditions. Don’s not a guy who works well with restrictions, and try as he might to meet the conditions of his rehiring, he crosses a boundary, and Jim Cutler tries to have him fired in “Waterloo.” Cutler also wants to make Harry a partner, which is a step too far. Then Bert dies unexpectedly, and that leaves Roger in a real pickle.

The partners vote in favor of McCann buying SC&P.

Roger he goes on a meeting with Jim Hobart of the great and powerful McCann Erickson, and the two lay their cards on the table. Roger wants to strangle Cutler’s power plays, and Hobart wants the Chevy team onboard so his agency doesn’t lose a Buick account. If McCann just buys SC&P outright, everybody wins. Well, sort of. Roger lays out this plan, and Joan and Pete practically faint when they realize how much money they’ll be making. The partners — who are now Roger, Don, Joan, Pete, Ted, and Jim — all vote in favor of the sale, even as the ghost of Bert Cooper reminds Don that the best things in life are free.

McCann brings SC&P in-house.

Which brings us pretty much up to date. In “Time & Life,” McCann decides to bring SC&P in-house completely, which everyone balks at, even though that seemed inevitable. Even with the PPL merger back in season two, this sort of thing seemed likely: “You bought us,” Bert Cooper said then. “We don’t expect to maintain autonomy.”

In some ways, the Sterling Cooperites are getting everything they wanted, account by account, pharmaceutical by Coca-Cola by car. (And, uh, something for Joan.) Most of them are an order of magnitude richer than their parents, and some will never have to worry about money ever again. Except Peggy wants to “create something of lasting value,” and Don’s convinced there’s more out there, and Ted just wants to have chill vibes. And maybe you can do that at a gigantic megacompany. But it’s a lot easier to do that somewhere else.

* This article originally misidentified the unlucky fellow whose foot was run over. And right when he got it in the door.