Qadesh 1300 BC

The mighty empires of the Pharoah's and the Hittites came to blows about the year 1300 BC near the town of Qadesh in Syria.

The town of Qadesh is about 600 km from the centre of power for each of these kingdoms. The typical army speed of the times was 25 kilometres per day. Therefor each army needed about 30 days to get to battle and 30 to return (i.e. a 60 day campaign). Lengthy battles seldom occured as most ended in 2 to 3 days. The constrcition of provisions could well be the reason.

In this late bronze age, battles were often fought after the harvest time of May. With the serfs being freed of chores, the leaders put them into the army and headed out to make war. This all came at an energy cost.

Hittite energy costs

In their army, they had;

• 3700 chariots each with 3 horses
• 40 000 infantry

A man marching with full gear would need 3600 kCal a day. Similarly, a horse pulling a laden chariot needs about 25000 kCal of digestible energy a day. Given this and assuming that the number for the Hittite infantry includes their charioteers then their daily energy needs would be;

Men + horses = 40000x3600 + 3700x3x25000 = 4.2x10¹¹Calories each day.

And for the campaign of 60 days, the total energy needs would be 2.5x10¹³Calories.

Egyptian Energy Costs

The Egyptian logistic issues were similar to the Hittites. Each kingdom's centre was about equal distance from the town of Qadesh hence each had to travel the same distance. Also each army likely travelled at the same pace so their traveling time would be the same. In the Egyptian army there were;

• 4 corps of 5000 men each
• Each corp included 4000 infantry and 500 chariots each with 2 charioteers running two horses.

Their total energy expenditure is thus;

Men + horses = (4000x4 + 500x2x4)x3600 + 500x2x4x25000 = 1.72x10¹¹Calories.

And for the campaign of 60 days, the total energy needs would be 1.0x10¹³Calories.

Total

The total energy cost would be about 3.5x10¹³ Calories (8.36x10¹²joules) though this assumes all the people and horses who went to battle also returned. This amount of energy is on the same scale as the amount of energy needed to launch the space shuttle into orbit.

This is a huge quantity of energy but only includes food. The energy needs to dress each person, build the chariots and manufacture all the spears, bows, arrows, and knives would increase this amount.

Energy Source

The energy source is the net primary production in the area. This must be a surplus from that needed to feed the farmers, adminsitrators and other support elements for the army. Today's wheat yields about 3.5x10⁹ calorie per tonne. Ancient wheat, without the genetic refinement, likely was less than a tenth the source of energy, or 3.5x10⁸ calories per tonne. Therefor, this campaign would need 10 000 tonnes of wheat (assuming all food came from wheat). The going rate was about a tonne per hectare so the campaign would need the excesses from 50 000 hectares (or 500 square kilometers. I.e. a tenth the area of present day Lebanon).