They used the stars to guide them, in the northern hemisphere Polaris is always to the north. They can also use where the sun and moon rise and set. Rises in the east sets in the west.
The main aggressor during WWl is considered to be Germany.
The USS Maine was sunk in the Harbour of Havana, Cuba, during a revolt of the cubans against Spain. Public opinion in the USA was that Spain was to blame. Starting as a diplomatic issue between Spain and USA, rapid escalation resulted in war between the two countries.