Eniac was indeed impressive and an important milestone. I recommend the 1999 book "ENIAC - The triumphs and tragedies of the world's first computer" by Scott McCartney which is both interesting to read and very informative. Also the review of the book by the late Jean Bartik, one of the "computers" and thus an eyewitnmess, is very interesting: https://web.archive.org/web/20221101120020/https://www.amazo....

Though the article is very US focussed, keeping quiet that German engineer Konrad Zuse completed the Z3 in May 1941, five years before ENIAC, effectively creating the world's first working programmable and fully automatic digital computer. While ENIAC required days of manual cable patching to program, the Z3 was quickly programmed by a punched tape ("Lochstreifen"), and Zuse also has invented Plankalkül between 1942 and 1945, which is widely recognized as the world's first high-level programming language. The cooperation between Zuse and ETH Zurich eventually led to the first self-compiling compiler and eventually Algol 60 (see "The European Side of the Last Phase of the Development of ALGOL 60" by Peter Naur in ACM SIGPLAN "History of Programming Languages" from 1978). And there was also the British Colossus, which was also a "programmable computer" and successfully utilized vacuum tubes for code-breaking by early 1944.