The "British Invasion". A question for you old farts out there.

Yes, early garage rock was an American thing, and my preferred music at that time. Bands like Beau Brummels, The Seeds, Count Five, Music Machine, Syndicate of Sound, Unrelated Segments, Zakary Thaks, Electric Prunes, Blues Magoos, Question Mark & Mysterians and The Litter. This was the music I related to with all my adolescent angst, which then led into the psychedelic era, .
Brits evolved in a different direction, all is good in my book, still listen to all these genres occasionally.

And yes, I did like DC5, Bits and Pieces really a garage rock song, heaviosity!

Actually, I remember the much bigger 'rivalry' was between the Beatles and the Monkees. Any DC 5 rivalry would have been over pretty quickly...

You've got to remember that The Beatles hadn't matured yet in 64 and 65.  They were still a teen pop band not that different from the DC 5.  Looking back on their entire careers, there's no comparison, but in the early days the DC 5 were competition for the Fab Four.  From Wikipedia:

The Dave Clark Five, often called The DC5, were an English rock and roll band formed in Tottenham in 1958. In January 1964 they had their first UK top ten single, "Glad All Over", which knocked the Beatles' "I Want to Hold Your Hand" off the top of the UK Singles Chart. It peaked at No. 6 in the United States in April 1964.[1] Although this was their only UK No. 1, they topped the US chart in December 1965, with their cover of Bobby Day's "Over and Over". Their version of Chet Powers' "Get Together" reached No. 8 on the UK Singles Chart retitled as "Everybody Get Together".[2]

They were the second group of the British Invasion to appear on The Ed Sullivan Show in the United States (for two weeks in March 1964 following the Beatles' three weeks] the previous month). They would ultimately have 18 appearances on the show. The DC5 were one of the most commercially successful acts of the British Invasion, releasing seventeen top 40 hits in the US between 1964 and 1967, and were briefly considered serious rivals to the Beatles. The group disbanded in early 1970. On 10 March 2008, the band was inducted into the Rock and Roll Hall of Fame.[3]

The Monkees were a manufactured band cast for a TV show, and the music was written mostly by Boyce and Hart and others and performed by serious studio musicians. Some nice stuff, but although very popular it was barely them although they could play and sing somewhat...Mike Nesmith is a relatively well regarded musician and songwriter and I think was the most substantial talent among those guys.