The star formation history of Trumpler 14 and Trumpler 16

H-R diagrams are presented for the very young galactic clusters Trumpler 14 and Trumpler 16, which are the two most populous clusters in the region of vigorous star formation surrounding eta Carinae. Point spread function photometry of UBV CCD images is presented down to V approximate to 19 for over 560 stars in Tr 16 and 290 stars in Tr 14. We have also obtained similar data for a local background field. After determining cluster membership through proper motions from a previous work, we find that the reddening of cluster members is significantly lower than that of the local background stars. Thus, we are able to use individual reddenings to identify likely members at far deeper levels than possible with proper motions. This work has revealed a significant population of pre-main-sequence (PMS) stars in both clusters. The location of the PMS stars in the H-R diagram indicates that the theoretical "stellar birthline" of Palla & Stahler follows the locus of stars far better than that of Beech & Mitalas. Comparison with both pre- and post-main-sequence isochrones also reveals that although intermediate-mass stars have been forming continuously over the last 10 Myr, the high-mass stars formed within the last 3 Myr. There is no evidence that the formation of the intermediate-mass stars was truncated by the formation of the high-mass stars.