The following .do file appends Gleditsch-Ward numbers to datasets based off of the country name. The file accommodates many, though not all, alternative spellings, and has been amended over time to include the spellings used in most frequently-used and publicly available datasets in IR. It can also be easily amended as you go to add the 2 or 3 new spellings necessary a new datasource.
There are two versions of the file -- one for standard capitalization and one for all-caps country names.
These .do files were first created by Håvard Strand and others at the Center for the Study of Civil War at PRIO, and I have merely expanded them.
RESHAPING DATA FROM THE WORLD DEVELOPMENT INDICATORS
This .do file provides a template for reshaping data downloaded from the world development indicators. Hopefully the means of adjusting the file for the particular set of variables you have downloaded is fairly self-explanatory. Make sure that you download all years beginning with 1960.