It crashed randomly when I sopke to the Americans.

Note that this is the very first version of Civ 1 for MS-DOS, labelled 474.01 or 475.01. In later versions labelled 474.03 (https://archive.org/details/CIVILIZATION_201902 ) or greater, probably easier to find, there were some changes in the game rules. Most changes were also kept in conversions for Windows etc. and in Civ 2.

Some changes are relevant for experienced players and make v03 harder for people playing aggressive despotism only. Main differences:
- v01: rate of unhappy citizens is constant. v03: large empires with primitive governments get extra unhappiness, and even red citizens with double unhappiness may appear
- v01: no limit on martial law. v03: no more than 3 military units per city can suppress unhappiness
- v01: maintenance cost of barracks is 0/1/2 depending on epoch. v03: it's 1/2/3 or 2/3/4 at harder levels
- v01: taxmen and scientists always available. v03: only in cities of at least size 5
- v01: transports may create unhappiness under republic or democracy
- v01: cities can't be renamed
- v01: there is a cheat/debug mode (shift-56)

Here is the first edition of the game manual, valid for v01:
https://archive.org/details/civilization-1-manual

For a middle schooler I was inpressed