Split-cour airing format is a noticeable trend in the anime industry recently. Unlike most multi-season shows that are aired two or more seasons in succession, split-cour shows have a break in between that usually lasts 3 months (1-cour). However, these cours are produced as a single product over the course of several months, not two separate anime, per se. For more information on cours and split-cours, this question might help.
Recent examples of anime that followed this format are:
Space Dandy - Winter 2014 [break: Spring] Summer 2014
Hitsugi no Chaika - Spring 2014 [break: Summer] Fall 2014
Aldnoah.Zero - Summer 2014 [break: Fall] Winter 2015
Tokyo Ghoul - Summer 2014 [break: Fall] Winter 2015
Some upcoming anime that are announced to be split-cour are Durararax2, F/SN UBW, and the Grisaia VN franchise, though I'm not really sure. Anyway, as the title states: I want to know what was the first anime that used this format of having a 3-month break in between cour/s.