I read in a book that the first radar was a CW one that was used to detect ships. Since it was CW, did it use Doppler to detect the moving ships? What was the signal processing used in it? Is there any reference to this information?
Indeed, in the very first time of radar, the technology necessary to measure delay between transmited and received echoes wasn't avaible for EM waves. I think that these first type of CW radars weren't used for ranging, only for detection. Using only one sensor which emit and receive the CW signal you can't perform ranging. In a bistatic configuration, i.e. the transmitter and the receiver arn't colocated, you may perform rangin by imposing a constraint on the target's kinematic (for instance, constant speed) and integrating measurments over time. Using a network of sensor (so called multistatic configuration) you may perform "real time" ranging without having to integrate measurments nor imposing a kinematic model on the target's motion.
Direct answer : These early radar were used only for detection and not for ranging.
Skolnik, M.I., Introduction to Radar Systems, 2ed., McGraw-Hill, 1980; there may be later editions.
In Eaves, Jerry L. & Reedy, Edward K., Principles of Modern Radar, Van Nostrand Reinhold, 1987, p.4, Table 1-2, mention is made:
"1903 Hülsmeyer (German engineer) detected radio waves reflected from ships.
1922 Marconi made a speech to the Institute of Radio Engineers (now the Institute of Electrical and Electronics Engineers) urging the use of short wave radio waves for detection of objects.
1922 Tylor and Young at the Naval Research Laboratory (NRL) detected wooden ships with CW radar having a 5-m wavelength.
1930 Hyland (NRL) detected aircraft with CW radar."
Note that some of this information is possibly incorrect. In the next reference, it's stated that Marconi made the 1922 speech to the Institution of Electronic Engineers (London).
https://en.wikipedia.org/wiki/History_of_radar. Note especially reference 33 - Hyland, L.A., A.H. Taylor, and L.C. Young; "System for detecting objects by radio", U.S. Patent No. 1981884, 27 Nov. 1934