Went to this show to see Yes for the first time. Incredible! Saw them 50 times more, up until 2018. Instantly became Humble Pie fan especially after "I Don't Need No Doctor". No Black Sabbath that night. Whatever. Yes significantly changed my musical direction. Actually Sabbath did also, but not that night. Picked up first BS album on a whim after initial release and after listening to the first cut asked my buddy I was with "What the hell is this?" Loved it! Easy to impress when I was 20. Still a progressive metal fan. Dream Theater rules!

Yes opened up for Humble Pie and headliner, Black Sabbath. No one had really ever heard much of Yes here until that night. A short, but outstanding set. Revolutionary!! Held their own with Humble Pie, a crowd favorite. Black Sabbath was a total downer and was literally booed off the stage! The next day not a copy of The Yes Album could be found anywhere... but I found one. It changed my musical life. The music that I create is heavily influenced still.Yes was all the music I ever loved rolled up into one band.

My memory of this show (clouded as it may now by age and then by a pre-concert beverage or two).
I went for Humble Pie. I didn't know that there would be a third band playing. Out comes Yes playing music that I never knew was possible. A wonderful set that had the entire audience standing, cheering and smiling.
As someone else posted, Sabbath was booed of the stage!
I was at the earlier of 2 shows, I was told that Sabbath refused to play the second show because they were upstaged by Yes.
I was young then, and this was one of my first concerts. I've been to many since but this is one of my top 2 or 3 all time.

Yes and Humble Pie blew Sabbath off the stage. I had never heard anything like Yes before that show and became a life long fan afterward. Great musicianship! Yes, opened the show! We do not even know that there was an opening band. And it ends up being Yes. Unbelievable.
Humble Pie rocked the Capitol to its core.
Marriot and Co. had the place rocking.
Then Sabbath came out, and were terrible.
Basically booed off the stage.

I was at the first show 7/14/71... and Black Sabbath did play...But were blown off stage by opener Yes... we'd never heard them... They were fantastic... Then Humble Pie with Frampton turned in a great rocking set of straight up British Blues... great Frampton solo's etc... Then poor simple Black Sabbath came out.... terrible... Most of us actually came to see Sabbath...(yeah... young stupid guys)... It became clear how simple and basic and boring Sabbath actually were... Ozzy... realized how bad it was...(Kind of like when Hendrix toured opening for the Monkee's).... Ozzy kept apologizing... Said his voice wasn't working... It was the crummy songs... Great show...until Ozzy...

I also went to see humble pie and was blessed to see my Yes Show Five hippies in a 59 Volkswagen saw the show of our lives

I was at this show, going to see Humble Pie and Black Sabbeth. But Yes was so great, I ended up rushing out to get the available albums. I have been a "Yes" fan ever since. All I can say is "Ozzy who?"

To this day I still tell people of the most amazing bill of Yes (opening), Humble Pie (on second) and Black Sabbath (headliner). And yes, it's true that Humble Pie blew Black Sabbath off the stage, so badly, that the following night Ozzy refused to leave the hotel room and play. I bought the Yes album right after this concert...and it changed my life. I'd never heard music quite like this. My few memories were of Tony Kaye set up extreme stage left, and Bill Bruford used to like to get up and walk around out front of his drum kit between songs. Maybe he had nervous legs. And earlier I had seen the whole band walk thru the stage door going in.
The Capitol still stands in Port Chester, but has not had live music shows there in years. It was a great place...second best only to the Fillmore East.