Online learning has become popular in the delivery of history materials. However, not much of the history learning material that is available online has a high level of understandability. Furthermore, not all history course designers and teachers are good at information technologies. To this end, an online history educational system, HES-SPATO, was developed. HES-SPATO is based on SCORM (Sharable Content Object Reference Model) to ensure reusability, durability, accessibility, and interoperability of electronic material. SPATO (Spatio-Person-Attribute-Temporal Object), the backbone of HES-SPATO, is designed to integrate the indispensable elements of historical events such as space, person, action/attribute, and time to increase the understandability of online history learning materials. In HES-SPATO, history SCOs were formed by integrating SPATOs with the associated "Space", "Person", and "Action/Attribute" assets, stored in the Asset Pool. SCOs, then, formed other SCORM components such as lessons and courses accordingly. The authoring module of HES-SPATO can enhance the history teachers' ability for creating online materials in a few guided steps with flexibility. HES-SPATO applies temporal logic to reason the temporal relationships between historical events. By applying the GIS concept of information layers, the learning module of HES-SPATO allow students to select different features with different layers to visualize historical events more clearly according to their own needs, zoom in to see features at closer range, view a variety of supplementary learning material at the same time and view SCOs according to their own progress and learning paths. It can also present specific information directly related to the historical event only, as defined in SPATO, to reduce cognitive load. With these developed functionalities, HES-SPATO can effectively reduce the teacher's burden and increase the understandability of history learning materials. Three teachers, who had taught general college history courses to non-history majors for more than ten years, were invited to evaluate both the authoring and learning modules. After these history teachers using HES-SPATO, semi-structured interviews were conducted to acquire their feedbacks in terms of processes to prepare history learning materials, understandings for students' learning history, responses for the map functionalities, and suggestions of the content and the history learning material displaying methods. The results of this interview demonstrated the teachers' acceptance of HES-SPATO and confirmed its helpfulness in teachers' preparation of online learning materials and students' understanding of history learning.