Brian made it clear that his ambitions had not been satisfied by the compromise of 997 when, in the year 1000, he led a combined Munster-Leinster-Dublin army in an attack on High King Máel Sechnaill mac Domnaill's home province of Meath. The struggle over who would control all of Ireland was renewed. Máel Sechnaill's most important ally was the king of Connacht, Cathal mac Conchobar mac Taidg (O'Connor), but this presented a number of problems. The provinces of Meath and Connacht were separated by the Shannon River, which served as both a route by which Brian's naval forces could attack the shores of either province and as a barrier to the two rulers providing mutual support for each other. Máel Sechnaill came up with an ingenious solution; two bridges would be erected across the Shannon. These bridges would serve as both obstacles preventing Brian's fleet from traveling up the Shannon and a means by which the armies of the provinces of Meath and Connacht could cross over into each other's kingdoms.