Which Linux distribution was the first to ship systemd as the default init system? Fedora was the first major Linux distribution to enable systemd by default, doing so in Fedora 15, released in May 2011. It replaced Upstart as Fedora’s default system and service manager.
Systemd had been introduced in 2010 by Lennart Poettering and Kay Sievers, who wanted a faster, dependency-aware alternative to traditional System V initialization. It could start services in parallel, activate some services on demand, track processes with Linux control groups, and manage more than the initial boot sequence.
The wording “first” matters. Fedora is generally credited as the first major distribution, rather than necessarily the first experimental or niche Linux project to package or test systemd. Arch Linux later adopted systemd as its default in 2012, while Debian made it the default in Debian 8 “Jessie” in 2015. Ubuntu followed with Ubuntu 15.04 in 2015.