Originally Answered: 60's Dance Party Vol. 3~ Woodstock 1969 vs. The British Invasion which one had the larger impact in rock?
That is a quite difficult question, in part because they are so different and in part because they are so related.
The British invasion ran for several years. Pretty much started with the Beatles three appearances on Ed Sullivan. They were followed with one band after another being introduced in the US over the next several years. Bands like the Who were part of the British invasion. Jimi Hendrix was at the time was thought to be part of the British invasion. Sure Hendrix was a back up blues guitarist for quite some time. But he had his break through in Britain with the Jimi Hendrix Experience. We did not realize at first he was from the northwest. By contrast, Woodstock was a single event. The festival for 3 days of peace and love. Hard to compare a single event with a multi-year event.
Also, there were bands who performed at Woodstock who were part of the British invasion. Case in point, the Who. This overlap makes it hard to distinguish between the two. In addition to the actual overlap, there is some other connections. The idea of the outdoor rock festival did not begin with Woodstock. Two years earlier, there was the Monterrey Pop Festival. That really laid the ground work for Woodstock. Even many of the performers at Monterrey played at Woodstock. Just to cloud the distinction even more, two of the board of organizers for Monterrey were George Harrison and Paul McCartney. Even though the Beatles, as a band, could not get clearance to play at Monterrey, two of the band's members were very active in organizing the festival. So, if you speak of Woodstock as an major outdoor rock festival, then you are talking about a concept that was partially forged by two of the people who started the British invasion.
Woodstock was probably the greatest single event in rock history. But it did not really become anywhere near as big an impact until the movie about it came out later. Most of my friends never heard about it until the movie. I had became a Hendrix fan sometime in 1966 (yes, I am that old). I actually talked about going to Woodstock with my (then) girlfriend. I missed Monterrey and I would like to go Woodstock because many of the same people were going to play there. I got talked out of going because of the distance. We hit some other festivals not so far away. (That proved to be a bad decision. Goose Lake was not nearly as good even if Life Magazine did a photo spread about it). So, I knew about Woodstock and maybe 4 or 5 other people on the college campus where I attended knew about it before hand. Then in 1970, my little sister and all the hippie want-a-bes told me about the great guitarist they discovered and how I should find out about him. Yep, Jimi Hendrix. Yes, they also discovered the Fish, only because of the fish cheer in the movie. None of them knew I had Jimi Hendrix's and Country Joe's records for a couple of years already. Point is, the festival was not know at the time. The movie make it known.
Contrast that with the Beatles on Ed Sullivan. Everyone heard about that and if they missed the first show, they caught the second or third one. So, at the time they each happened. the British invasion had a much bigger immediate impact. Even the anticipation was more wide spread for the British invasion. Everyone knew the Beatles were going to be on TV. Very few knew Woodstock was going to happen.
The outdoor rock festival concept (which really started with Monterrey) continued. Throughout the 70s there are so many of them. I lost track of the ones I went to, not to mention all those I did not even know about. The mega-concert concept really made it next big leap when George Harrison organized the Concert for Bangladesh. That was the first major charitable rock event. That concert was an outgrowth of Woodstock. (In turn was an outgrowth of Monterrey) And, that concert was organized by George Harrison (one of the organizers of Monterrey). That concept has continued well past the 70s. Therefore, the concept has been very significant.
Another aspect of the analysis, is that Woodstock really presented nothing new to US music audience. I had listened to the Who, Country Joe, Canned Heat, Big Brother and the Holding Company, Jimi Hendrix Experience, Richie Havens and others for a few years before Woodstock.
In contrast, the British invasion brought a whole new sound to the US. The British invasion sound so quite different than the Beach Boys, Jan and Dean, Duane Eddy and the rest we were listening to at the time. The British invasion really introduced a new era in rock music to the US.
Well, I rambled on pretty good there. Don't know if I actually answered your question. Don't know if there is an actual answer to the question. Guess, I just gave you the thoughts of a long time rocker.